WC into understairs pantry - queries... anyone here?

As far as plumbing goes, from your pics.
Looks like an S-Trap pan, so sewer goes into floor. ( No need to extend waste through wall)

As far as Plumbing is concerned.
Get a jackhammer. Jackhammer up floor in pans current location and to a point where new pan is to be relocated.
Continue to Jackhammer up floor to point where sink is to be located.
Install below ground sewer to locations required.
Install water supply to new fixture locations

The rest is cosmetic, so no plumbing input required - bar fitting pan and sink.


*This is assumed the floor is concrete.

Thanks for reply.

So jackhammering up the concrete is certainly a solution, but considering the new pantry WC is on the other side of wall with a floor that is 2 bricks higher than the current garage WC floor - I don't see how that is an easy option. Jack hammering up the concrete to the sink location or the shower waste - will mean we have know where they should be upfront and it will not be easy to change that for any reason (and it may need to change as you never know where things need to be until you try and fit them).

How about the below...



(A) This is the new raised wooden floor that will be level with the pantry floor on the other side of the wall. This floor will also be level with the kitchen floor and provide easy access to the new garage shower room from the kitchen. On this raised floor will be the new shower tray - probably on a plinth as the new pantry WC 110mm waste pipe (B) will have to go above that floor and then go through to the pantry new WC (save anyone having to dig up the pantry floor).

(B) This is the soil waste pipe plumbing. Probs consist of a 4" to 110m fitting from the current floor collar - then a 90 degree bend - a waste connection for the garage sink and shower - and then an extension to go through to the new pantry WC.

(C) This is the waste connection to the sink and waste. I am not sure if this should be before the bend or after (as show in pic). I am thinking that it can be after the bend as the 110mm pipe will have to have a plinth above it and then the waste pipe can go under that to the traps in the shower and sink connection. The waste for the shower could be on the furthest side from the pantry wall which would make it easy to access for any maintenance. I understand that the shower tray plumbing pipe needs a fall.


I guess my questions are:

1) Does this design make sense - or any major issues with it? I am thinking maintenance and access for issues in the future as well?

2) If I dug up the pantry floor I could run the new WC waste pipe extension under the new garage floor (A) and thus avoid having to put the shower on raised plinth - but I don't want the hassle of digging up the pantry floor - is this a bad move?

3) If the (C) waste connection is after the bend - are the falls from a shower tray not going to be possible under a shower plinth unless it is a very high plinth (as the shower hole will be other side of the tray for maintenance access).

4) Should I have the (C) waste connection before the bend to ensure enough fall gradient for the piping from the shower tray waste? I could put a small floor trap door access to get to the shower piping if that's a good idea?

5) Will the shower tray and sink connections stop any chance of fouls smells from the new pantry WC piping coming up from the sink or shower waste?

Welcome any replies.

Everything you're asking depends on the depth of the existing drain you are intending to connect to.

Once you've determine the depth of the existing graded horizontal drain you can work out what you need to do for the rest.

oz-plumber said:

Everything you're asking depends on the depth of the existing drain you are intending to connect to.

Once you've determine the depth of the existing graded horizontal drain you can work out what you need to do for the rest.

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Hi - the depth of the clay soil pipe that is running into the garage from underground?

Really? But am connecting form the clay collar upwards and into the pantry - so hows the depth of it under the ground matter?

This isn't plumbing questions but wondering if anyone has a view on WC pantry flooring...

I was told it was quarry tiled floor and should not put plywood on top for lino as it would sweat. It does seem a bit damp as possibility there is no ventilation in the pantry currently.

Is it desirable to expose this traditional tiled floor? Can it be improved somehow, polished or cleaned easily?

Or if the floor is not that level, is it better to put some self level compound on it and finish it off with some flooring?

advicewelcom said:

This isn't plumbing questions but wondering if anyone has a view on WC pantry flooring...

I was told it was quarry tiled floor and should not put plywood on top for lino as it would sweat. It does seem a bit damp as possibility there is no ventilation in the pantry currently.

Is it desirable to expose this traditional tiled floor? Can it be improved somehow, polished or cleaned easily?

Or if the floor is not that level, is it better to put some self level compound on it and finish it off with some flooring?

Click to expand...

If your property is Victorian or Edwardian, there is probably no damp proofing beneath the quarry tiles, they may be laid on the earth, or cement or sand directly on the earth. If you cover them over with anything you will be inviting damp to creep up the walls. If you can leave the floor as it is (I would!) and keep the room ventilated, you shouldn't have any damp problems.
There are ways to clean the quarry tiles - cement removing acid and abrasion to clean them. Worth looking on internet forums etc. Broken ones can be carefully replaced - EBay has period tiles on sale for example, and there are specialists for spares. You can treat/polish them when clean, but you need permeable products to allow moisture through.
I've had a number of period houses from the 1500's to Edwardian, and learnt that the less you interfere with the original construction, the better. Modern materials generally just cause side effects that get worse over time than the original issue you had 🤪

Thanks for the reply. Its a semi - so I suspect its a 1940s build. I am sure these tiles are under the entrance hallway carpet as well (near the front door). I guess I would need to chip away and take one up to be sure what its lying on? And cement it back down?

Found this, which seems to provide some guidance along with your reply.
Ultimate Quarry Tile Cleaning Guide - Professional Tile and Stone Restoration - https://tilelife.uk/ultimate-quarry-tile-cleaning-guide/



The plumber guy was going to come and slap self levelling compound over them as floor is a bit uneven. Your saying this is not a great idea, try clean them up and add a ventilator fan in the space - as the best approach? Plywood ontop with some lino is not really and option - or can be for short term? I guess tiling on top with some Victoria design tiles is not a long term option either?

advicewelcom said:

Thanks for the reply. Its a semi - so I suspect its a 1940s build. I am sure these tiles are under the entrance hallway carpet as well (near the front door). I guess I would need to chip away and take one up to be sure what its lying on? And cement it back down?

Found this, which seems to provide some guidance along with your reply.
Ultimate Quarry Tile Cleaning Guide - Professional Tile and Stone Restoration - https://tilelife.uk/ultimate-quarry-tile-cleaning-guide/

The plumber guy was going to come and slap self levelling compound over them as floor is a bit uneven. Your saying this is not a great idea, try clean them up and add a ventilator fan in the space - as the best approach? Plywood ontop with some lino is not really and option - or can be for short term? I guess tiling on top with some Victoria design tiles is not a long term option either?

Click to expand...

If it's 1940's there might be a DPM, in which case you could do what you like over the top. You really need a damp meter (and learn how to interpret it!) to check for damp, or if you know it's damp then I would suggest perhaps not putting anything over the top.
A latex self levelling screed is not permeable, so that's like putting waterproofing over your floor, which, If there is damp, will eventually give you damp up the walls because it can't get out through the floor! Then the plaster blows and mold etc and you end up having to inject the wall with damp proofing, which either does nothing or it pushes the damp to pop up elsewhere!

But as I say if there is a damp proof membrane under the floor and at the bottom of the wall, you should be fine. You could excavate a little to find out how it's built.
You might get away with marine ply for some years, but you could get mould and eventually plaster blowing as a result.
If you tile over the top with permeable tiles (not porcelain or glazed ceramic, maybe limestone or clay pavers ok?) and the same for the adhesive and grout, you might be OK

Basher said:

If it's 1940's there might be a DPM, in which case you could do what you like over the top. You really need a damp meter (and learn how to interpret it!) to check for damp, or if you know it's damp then I would suggest perhaps not putting anything over the top.
A latex self levelling screed is not permeable, so that's like putting waterproofing over your floor, which, If there is damp, will eventually give you damp up the walls because it can't get out through the floor! Then the plaster blows and mold etc and you end up having to inject the wall with damp proofing, which either does nothing or it pushes the damp to pop up elsewhere!

But as I say if there is a damp proof membrane under the floor and at the bottom of the wall, you should be fine. You could excavate a little to find out how it's built.
You might get away with marine ply for some years, but you could get mould and eventually plaster blowing as a result.
If you tile over the top with permeable tiles (not porcelain or glazed ceramic, maybe limestone or clay pavers ok?) and the same for the adhesive and grout, you might be OK

Click to expand...

Thanks for reply. The DPM is the key then.

The Garage WC is a couple of bricks lower on the other side of Pantry wall. Below arrow shows the context:




If I look at the Garage wall - would I be able to visually see a DPM or a tell-tale-sign - and can march forward confidently?



Don't think there is anything there looking at the picture? Or is meter testing or taking up the pantry floor - the only way to know for sure?

It's tricky to tell!
If the garage wall hadn't been painted, you would stand a chance of seeing if there was a bituminous or slate or whatever damp proof section of pointing.
Are there any sections of brick wall round the house (unpainted), where you might see a sign of a DPC in the pointing?
But my old Edwardian house had a DPC in the (solid) outside walls, but the quarry tiles and pamments inside were still laid on the earth with no DPM underneath!

Taking up a quarry tile would be the best way, but it's tricky to remove a whole one without disturbing others, and if you take up a broken one (easier) then you will need to buy replacement(s)!

Looking at the pics of the pantry, I would guess a moisture meter would say it's damp, so you're no further forward doing that!

If you could live with the quarry tiled floor as is, or tidied as you wish, or otherwise covered with a hessian mat or rug, (as long as it's permiable), that could be simplest!

Basher said:

It's tricky to tell!
If the garage wall hadn't been painted, you would stand a chance of seeing if there was a bituminous or slate or whatever damp proof section of pointing.
Are there any sections of brick wall round the house (unpainted), where you might see a sign of a DPC in the pointing?
But my old Edwardian house had a DPC in the (solid) outside walls, but the quarry tiles and pamments inside were still laid on the earth with no DPM underneath!

Taking up a quarry tile would be the best way, but it's tricky to remove a whole one without disturbing others, and if you take up a broken one (easier) then you will need to buy replacement(s)!

Looking at the pics of the pantry, I would guess a moisture meter would say it's damp, so you're no further forward doing that!

If you could live with the quarry tiled floor as is, or tidied as you wish, or otherwise covered with a hessian mat or rug, (as long as it's permiable), that could be simplest!

Click to expand...

Hey thanks for that. Be great to keep floor as is - can get on with plumbing the WC in and the feeds and get things started in some way.

Hunted around to see what could be found with the DPM... I think there is a thicker layer around the base of the garage wall. Seems like the bottom of the air vent has a different texture then a brick - maybe something there - looks hopeful?...



Does this mean I have choices with the floor including self levelling compound?

With the current floor - tried mixing a bit of bleach, vinegar and flash and gave a tile a scrub with a wire brush - the tile seemed to come up okay...




But the floor is a bit wonky - so much the WC is a bit rocky on the uneven floor. If I keep the current floor, should I cut out a piece of mdf or something in the shape of the bottom of the pan and screw through that to the floor to make a pan plinth- will keep it a bit more steady and its not porcelain against tile? Anyone ever done that or is there something else to do - like buy one?

advicewelcom said:

Hey thanks for that. Be great to keep floor as is - can get on with plumbing the WC in and the feeds and get things started in some way.
Hunted around to see what could be found with the DPM... I think there is a thicker layer around the base of the garage wall. Seems like the bottom of the air vent has a different texture then a brick - maybe something there - looks hopeful?...
Does this mean I have choices with the floor including self levelling compound?

Click to expand...

Personally I wouldn't use latex self levelling compound or cover the floor without first establishing that there is a membrane or equivalent under the tiles. And I think there's a fair chance there isn't!

advicewelcom said:

With the current floor - tried mixing a bit of bleach, vinegar and flash and gave a tile a scrub with a wire brush - the tile seemed to come up okay...

Click to expand...

Looks like it could look good if you have the time to restore it.

advicewelcom said:

But the floor is a bit wonky - so much the WC is a bit rocky on the uneven floor. If I keep the current floor, should I cut out a piece of mdf or something in the shape of the bottom of the pan and screw through that to the floor to make a pan plinth- will keep it a bit more steady and its not porcelain against tile? Anyone ever done that or is there something else to do - like buy one?

Click to expand...

If you put plain wood or ply under the pan it will likely ultimately go rotten, though it'll take a while. Marine ply would last longer.
That method might not end up with the pan base perfectly horizontal, unless you fettle the sheet, or use spacers.
I would put a mortar ring to support the pan, or even use silicone!! But I'm not a professional plumber, so those here might have a different view.

Basher said:

Personally I wouldn't use latex self levelling compound or cover the floor without first establishing that there is a membrane or equivalent under the tiles. And I think there's a fair chance there isn't!

Looks like it could look good if you have the time to restore it.

If you put plain wood or ply under the pan it will likely ultimately go rotten, though it'll take a while. Marine ply would last longer.
That method might not end up with the pan base perfectly horizontal, unless you fettle the sheet, or use spacers.
I would put a mortar ring to support the pan, or even use silicone!! But I'm not a professional plumber, so those here might have a different view.

Click to expand...

Thanks for your replies, appreciate it.

Gave the floor a scrub and it cleans up okay (probs need a polish) but the room looks a bit like a damp cell as its small and the floor is dark colour - could do a lighter colour traditional floor tile in it to make it look better.

The man at flooring shop suggested a damp proof membrane solution before putting down self levelling compound.

Would this solve the issue and enable to move forward?

(Having nightmare trying to get a plumber in for the plumbing so 'ave to sort floor somehow quickity split).

advicewelcom said:

The man at flooring shop suggested a damp proof membrane solution before putting down self levelling compound.
Would this solve the issue and enable to move forward?

Click to expand...

A DPM, either paint on, or in the form of a sheet of plastic material, will stop damp coming through the floor, so new tiles and grout would be protected.
But if you do that, where does the damp go? It doesn't go away. As it's no longer evaporating through the old floor, the moisture content builds up and the bottom of the walls become wetter than before. Then, if there's no DPM in the walls, osmosis allows the water to creep up the wall (can be a metre), and the salts in the water appear on the surface of plaster, and can ultimately result in 'blown' plaster which comes away from the brick wall. Unsightly and can allow mould to grow.
Then you call in damp 'specialists' who render the wall in waterproof cement and waterproof plaster, which traps the water in the wall, probably to reappear elsewhere and/or cause damp smells!
From the point of view of looking after the building, and having least hassle long term, I wouldn't put a DPM down. I would put a permeable floor covering like a mat or hessian carpet or something like that to mask the existing tiles and brighten the colour. I appreciate carpet or a mat is not most practicable in a toilet, but it's easy to replace!

But that's just me. It's your house, and assuming it's not a listed building, you can do what you like with it!
If you don't plan on keeping the house for long, then you'll maybe get away with the DPM approach.
If you're going to be there for 10 years or more, you might regret adding a DPM because the walls might be looking a mess by then. Or it might be OK, I can't predict.

Thanks. Really appreciate the feedback. I do have to sort something out for this floor as plumber wants to get started.

Did try and scrub it up and it not looking that great really, horrible grout lines, its wonky and makes the small room look a bit dingy.



I can imagine that it would look okay on a porch cleaned up and lacquered - but in this small enclosed area its not that appealing.

The carpet is an idea but accidental spills on it aren't going to be easy to clean.

Ideally I would love to put some olde' looking tiles down.



And that requires a level floor.

I guess the key question is if the walls have DPM - if they do - the damp can't go up into the walls if cannot go through the. Is there any way to defo find out?

If I do go for DPM'ing the pantry floor, do I have paint on something like this on the tiles and give it time to dry?


Or could I just put this down and then plop the self level compound down on top of it?

Hi. I do appreciate you want to get this done!
I'm not a builder, so prob not the best person to advise, but to me the membrane sheet might be a good option, because the cracks in the tiles and lack of grout between them might mean the paint-on wouldn't actually seal, as in the cracks the liquid might run through and leave a gap for the damp to penetrate.
You would normally run the membrane sheet slightly up the wall, and when the screed is set, cut off the surplus round the edge.
I think you'd want a decent thickness slab of screed say 5cm or so, as otherwise it might crack or move as you walk on it. Then you would put the self levelling on top of that.
If you can't afford to build up the floor by that amount, then using the liquid (2 coats) would be better, as the screed/ self leveling compound would bond to the old tiles.
See Floor Screed Thickness - What Are The Minimum & Maximum Depths? - https://www.speed-screed.com/knowledge-centre/floor-screed-thickness/

Regarding 'is there a damp proof course in the walls', the way to find out would be to carefully excavate a bit of the horizontal pointing to see if there is bitumen/ slate/ plastic evident between courses of bricks at or under floor level. I gather from something I read recently that DPM in walls was mandated in the 1970's, so if your house was built before that, there might not be one.

Basher said:

Regarding 'is there a damp proof course in the walls', the way to find out would be to carefully excavate a bit of the horizontal pointing to see if there is bitumen/ slate/ plastic evident between courses of bricks at or under floor level. I gather from something I read recently that DPM in walls was mandated in the 1970's, so if your house was built before that, there might not be one.

Click to expand...

Thanks so much. Find myself in panic again on the weekend as have to make decisions quick.

The house is 1940's semi, but not sure about DPM. Do see this surface around the air vents in the garage and there is a line of something going underneath the step into the house. Never had an issues with damp internally on the walls so must be something there.




If the external walls have it, I hope the other original internal brick walls from the floor have it. I guess the only thing to worry about now is the floor damp and can be safeguarded against with some DPM paint or membrane, I hope.

Basher said:

Hi. I do appreciate you want to get this done!
I'm not a builder, so prob not the best person to advise, but to me the membrane sheet might be a good option, because the cracks in the tiles and lack of grout between them might mean the paint-on wouldn't actually seal, as in the cracks the liquid might run through and leave a gap for the damp to penetrate.
You would normally run the membrane sheet slightly up the wall, and when the screed is set, cut off the surplus round the edge.
I think you'd want a decent thickness slab of screed say 5cm or so, as otherwise it might crack or move as you walk on it. Then you would put the self levelling on top of that.
If you can't afford to build up the floor by that amount, then using the liquid (2 coats) would be better, as the screed/ self leveling compound would bond to the old tiles.
See Floor Screed Thickness - What Are The Minimum & Maximum Depths? - https://www.speed-screed.com/knowledge-centre/floor-screed-thickness/

Click to expand...

Thanks. Putting down screed is going to be out of my scope - it would need it to dry before adding the self levelling and its never going to get done without a new learning curve - also have limited access to a helper. Would ideally need to get the floor work done in one day of labour.

So the two options I would have to choose between are:

Option 1.
Membrane sheet and latex self level compound on top and cut of the surplus membrane around it (no other screed)
This could get done within a day and would have the week to dry off and then plumber in.
The self level compound is able to go to 10mm and the bag has enough for 5sqm but we only need 2sqm, so have plenty of depth to play with
Just hope its okay for the membrane to sit on top of quarry tiles unbonded and the self levelling compound to be on top of membrane?

Option 2.
Painting a thick coat of this DPM and then and latex self level compound on top of that?
This isn't my preference as will burn more time waiting for the DPM paint to dry and then will take another week to come back for the self levelling compound.
Unless I can plonk the membrane sheet on top of the wet DPM paint and then self level compound of top of that and be done in the same day (I suppose not)?

I think you are saying option 2 is better? And then have to come back next week for the self levelling compound once the DPM paint is dry?

I would like option 1 - no screed, just DPM membrane and self levelling compound - as it will get done in day - would it be okay?

advicewelcom said:

Thanks. Putting down screed is going to be out of my scope - it would need it to dry before adding the self levelling and its never going to get done without a new learning curve - also have limited access to a helper. Would ideally need to get the floor work done in one day of labour.

So the two options I would have to choose between are:

Option 1.
Membrane sheet and latex self level compound on top and cut of the surplus membrane around it (no other screed)
This could get done within a day and would have the week to dry off and then plumber in.
The self level compound is able to go to 10mm and the bag has enough for 5sqm but we only need 2sqm, so have plenty of depth to play with
Just hope its okay for the membrane to sit on top of quarry tiles unbonded and the self levelling compound to be on top of membrane?

Option 2.
Painting a thick coat of this DPM and then and latex self level compound on top of that?
This isn't my preference as will burn more time waiting for the DPM paint to dry and then will take another week to come back for the self levelling compound.
Unless I can plonk the membrane sheet on top of the wet DPM paint and then self level compound of top of that and be done in the same day (I suppose not)?

I think you are saying option 2 is better? And then have to come back next week for the self levelling compound once the DPM paint is dry?

I would like option 1 - no screed, just DPM membrane and self levelling compound - as it will get done in day - would it be okay?

Click to expand...

As I said, I'm not a builder/tiler!
It seems membrane sheet won't provide desired adhesion between the quarry tiles and SLC, and if you build up the SLC it can crack.
The usual way seems to be Option 2, with liquid DPM given a sprinkling of sharp sand when wet to provide a key for the SLC.
You can get quick-dry products which would allow all the necessary layers to be done in a day.
If you need to DIY it you could try this: ARDITEX NA Rapid Setting Levelling and Smoothing Compound - https://ardex.co.uk/product/arditex-na/,

Have you looked here : Tiling Advice | USA & UK Tiling Forum > Tilers Forums - https://www.tilersforums.com/

Basher said:

As I said, I'm not a builder/tiler!
It seems membrane sheet won't provide desired adhesion between the quarry tiles and SLC, and if you build up the SLC it can crack.
The usual way seems to be Option 2, with liquid DPM given a sprinkling of sharp sand when wet to provide a key for the SLC.
You can get quick-dry products which would allow all the necessary layers to be done in a day.
If you need to DIY it you could try this: ARDITEX NA Rapid Setting Levelling and Smoothing Compound - https://ardex.co.uk/product/arditex-na/,

Have you looked here : Tiling Advice | USA & UK Tiling Forum > Tilers Forums - https://www.tilersforums.com/

Click to expand...

Hi, thanks - your more of a builder/tiler then me - so will take any advise provided gladly.

Have to see if I can get a plan for this weekend as its been going on too long. Seems quarry tiles and damp mangement is something rightly flagged as an area of concern. Can't roll back easily if mistakes are made with flooring - so worth getting a plan together.

Some useful stuff on that tilers forum, but waiting for a confirmation email to access it fully.

Looked into the ARDITEX SLC - and it seems its used for self levelling compound to bond to damp floors which can then have a DPM put on top of it - from what I am seeing it can be used to avoid primers but unsure if its saying you don't need a DPM membrane with it? If fact some of the feedback states it can be used as initial layer, then DPM and then another layer on top "Easy to work as an initial leveller and then top coat for a DPM sandwich."

If I get helper in for a day - its going to be a pain to wait for anything to dry.

Considering I can't plop SLC on top of floating membrane, I think the revised options at the moment are...


1) ARDITEX SLC stuff, if it can just be put onto quarry tiles - could perhaps call the manufacturer to find out?

2) Painting DPM and using your sharp sand suggestion myself - and then getting helper around the following day (hopefully it will dry in a day) for SLC placement?

3) Hessian rug suggestion on the quarry tiles, maybe try cleaning tiles with an acidic tile cleaner? And either a WC pan plinth or silicone under the WC pan to prevent any seesawing on an uneven floor?


I could get one of these damp meters - if I took a measurement would it help direct the decision?

1) ARDITEX SLC stuff, if it can just be put onto quarry tiles - could perhaps call the manufacturer to find out?

Click to expand...

I think this could be a good way to go if you want to even the floor - worth a call for a sanity check

2) Painting DPM and using your sharp sand suggestion myself - and then getting helper around the following day (hopefully it will dry in a day) for SLC placement?

Click to expand...

Our builder has recently put a liquid DPM coating on top of the old screed of our period cottage kitchen floor, then scattered with sand. It dried quickly. They then put a latex screed over.

3) Hessian rug suggestion on the quarry tiles, maybe try cleaning tiles with an acidic tile cleaner? And either a WC pan plinth or silicone under the WC pan to prevent any seesawing on an uneven floor?

Click to expand...

Least hassle route (or maybe not with the tile cleaning!), but as you've pointed out, maybe not the most practical to keep clean. You've begun to convert me to the idea of screeding, but I still worry about damp ultimately affecting the walls. But I have no evidence there is a raging damp problem, so maybe I'm just being paranoid!

I could get one of these damp meters - if I took a measurement would it help direct the decision?

Click to expand...

Damp meters measure the resistance of what you stick them in. They are notionally "calibrated" for a few different materials. But the conductivity of materials is greatly affected by 'ionic contamination', ie dirt, salts from the ground, and other substances, so you need to be very aware of these factors as they often swamp the real moisture you are trying to measure. On the other hand if you got the meter, and it pronounced dryness, then you could be pretty confident you don't have damp!!

[/QUOTE]

Basher said:

I think this could be a good way to go if you want to even the floor - worth a call for a sanity check



Our builder has recently put a liquid DPM coating on top of the old screed of our period cottage kitchen floor, then scattered with sand. It dried quickly. They then put a latex screed over.



Least hassle route (or maybe not with the tile cleaning!), but as you've pointed out, maybe not the most practical to keep clean. You've begun to convert me to the idea of screeding, but I still worry about damp ultimately affecting the walls. But I have no evidence there is a raging damp problem, so maybe I'm just being paranoid!



Damp meters measure the resistance of what you stick them in. They are notionally "calibrated" for a few different materials. But the conductivity of materials is greatly affected by 'ionic contamination', ie dirt, salts from the ground, and other substances, so you need to be very aware of these factors as they often swamp the real moisture you are trying to measure. On the other hand if you got the meter, and it pronounced dryness, then you could be pretty confident you don't have damp!!

Click to expand...

[/QUOTE]

Thanks. Gave Ardex a call and spoke to there Business Dev guy. Knowledgeable chap and ended up with a techie talk about substrates, bonding, dpm's, slc's, etc. The rub of it was there were two solutions for quarry tiles using their product which is designed to bond to damp surfaces but not replace a DPM. That is...

1. PAINT DPM
If the quarry tiles are even, then his suggestion is to paint on a DPM and then within 6-48hrs put down the Arditex NA onto a tacky dry liquid DPM which will create a bond.

2. DPM SANDWICH
If the tiles are two uneven for even cover of a paint DPM then can do a DPM sandwich using their product - one layer Arditex then liquid DPM and then another layer Arditex.

Am learning that the product isn't hassle free to get hold off - most distributors require trade accounts and not many around as they don't sell that much of it. Prices vary between £30-£60+VAT 😳 for a 20kg bag and solution depending on distributor.

Am starting to think keeping the quarry tiles left as they are would be less hassle and can just get on with the plumbing.

I suppose, if needed, could just pull the WC pan out and do the floor if I can't live with quarry tiles when finished?

advicewelcom said:

Am starting to think keeping the quarry tiles left as they are would be less hassle and can just get on with the plumbing.

I suppose, if needed, could just pull the WC pan out and do the floor if I can't live with quarry tiles when finished?

Click to expand...

Seems you got good advice.
You could certainly do the plumbing first and then re-visit the floor later if unhappy with it.
But if the soil pipe is going through the wall horizontally as post #10 suggests, might be good to leave some vertical play in that pipe if the floor level might be raised later!
Sounds like you have good info now, just a question of deciding which way to go!
Good luck with the project.