Roof Repair

[WHPES]

Just been out to see a customer today with a leaky roof. I have the following secnario:

At the front of the building is a foyer approx 5m x 7m with a flat roof and a timber framed glass skylight canopy in the centre. The flat roof consists of lead bays forming a rectangle with the canopy in the centre. Around the edges of the roof is a lead box gutter (which is new as I replaced the old one last summer). There is a pitched roof above, below and to the left of the picture. All foot traffic to and from the hotel enters and leaves via this area.
The lead bays are approximately 0.8m x 1.5m (yes I know this is too long for modern standards but that isn't the problem).

The roof appears to have settled so that water is pooling by one side of the canopy and finding its way under the lead roll.

Obviously the way to do it properly is to lift the lead off and get my joiner to modify the timberwork underneath, making tapered timbers and laying them on top of the old ones to get the rise, then putting the lead back. I am considering redesigning some of the bays if the old lead is in too poor a condition to put back.

However this is obviously a major job and a job for ths summer. I told the customer that all I can do is to lash a tarpaulin over the entire roof to keep the water off the lead bays, but the customer (a hotel) doesn't want the foyer to be in the dark if possible. I am now thinking about heavy clear Visqueen sheeting but do you think this will hold or has anyone any other suggestions?

The picture is what I took last spring (The timberwork has since been repainted and the old glass replaced with toughened glass, I replaced the flashings on the glass, it has been cleaned since then!) Unfortunately the bays in question are at the RHS but they are similar to the left. The foyer is south facing (the RHS is facing south) so does not get a huge amount of weather.

 

[Renewable M]

Crikey.

I know this sounds obvious, but how long would it take to strip out, alter the timber and replace, say one side at a time? Could it be over sheeted with a scaffold, get stuck in and then the scaffold removed?

 

[WHPES]

Based on prior experience, we have estimated between a week and a fortnight for the total job. My joiner will rig up a temporary roof and sheeting above it. The timber will not take as long to fit as one may think as he will order the timber ready formed from the sawmill once he knows what he needs, which will save a lot of time.

Looking at the way the lead has settled, it would appear that the timbers run parallel to the guttering and canopy, so they need lifting and raising.

I will also put a layer of geotextile between the lead and the timber. The customer is also interested in my suggestion of installing Kingspan under the timberwork if practicable and if there is space. The original work I estimate to be 1920s based on the art deco features in the hotel and I doubt the leadwork has had much done to it since then, or that there is already any glass fibre insulation in place.

In my experience, it's easier to do the entire job in one go than a bit at a time. The customer would prefer this as it means minimal disruption to the guests. I have persuaded the customer to purchase any lead sheeting directly from the supplier as he is VAT registered whereas I am not.

The main issue with the work is getting the lead up, but we reckon that it can be lifted up on a pallet using a telescopic forklift in front of the hotel entrance. The roof is about 6m above the ground so it should reach.

If the lead is past re-using, I am planning to make smaller bays and form corner hips which I think are better and look really nice. This is a roof of a portico of a small country manor house I redid in 2006.

 

[justlead1]

Hi. If the pooling is shallow say 10 mm and the lead sheet is sound at the upstand, try pulling the overclock away from underclock on the roll, enough to stop and capillary action that may be taking place.
With out trying to be patronising, check that the condensation on the glass is not finding its way behind upstand at abutment. Being on the North side any condensation would be greater than other compass points. Good Luck

Hi. If you are pushed for time. We fabricate sheet lead bays with the roll abutment end formed. Normally 600 mm wide by up too 1800 mm long (code 5) The drip end rolls can be bossed as fitting. I would expect 14 bays to be fitted using this method i a day with two persons working. It allows the work to be done with a couple of days if you can see a weather window that looks favorable. It you want a quote get back to me with a few images and dimensions, the quote is free. We deliver anywhere. Good Luck

 

[WHPES]

The pooling is about 20mm in the worst place. I am reluctant to mess about with it at the moment as the weather is foul and sub zero, the gutters are full of ice and access is slippery. Also the lead has been tucked underneath the canopy flashings which are all firmly secured.

No, defnintely not condensation. Some thought has gone into the original construction - The sills on the inside below the lower glass panes have channels cut into them and a drip groove to take the water outside. There is also a gap between the top glass sheets and the timberwork to allow condensation to run out and ventilation to occur.

The problem is on the south side.

I may contact you later for a quote, but the roof is fairly small so I don't think it's too much of a challenge for us. I would normally go for code 6 but I seem to remember the LSA says Code 5 is OK for the size of bay.

The canopy and much of the roof is very visible from the outside due to the slope of the drive and the lawn towards the entranceway so any temporary cover will have to be neat. The hotel is used for functions throughout the year. Obviously the tap-tap-tap of lead working can't be going on in the middle of a wedding reception!

There is a lot of work I have already done and a huge amount of further potential work here so it is important to keep the manager sweet!

 

[ken quinton]

Hi there.
We work with and repair these type of roofs all the time. In and around
London.
If all the lead is in tact and it was layed properly. then they should
not leak even with 20mm of water laying on them.
The under-cloak of the seamed roll should reach the top of the wood
roll. 50mm.
Sometimes with the older lead bays the lead is weak where it was
bossed at the back of the bay where the rear upstand meets the
under-cloak. If there is even a small split in the lead there and water
is laying in the bay it will cause a large leak.
Ive had splits there that were only 10mm and took ceilings down.

The bays themselves can normally be lifted and replaced or renewed
one at a time.
Not sure if this is any help to you.
If you can give me more info on the problem, or some photos
i can probably tell you best way to fix it.
P.S Code 5 is o.k but is the minimum for sheet lead bays.
Geo-textile is only needed if the decking is uneven (old boarding or
concrete/screed). otherwise building paper will be fine.
good luck.. Ken

 

[jenroof]

That kind of roof repair could really hard. It would need more days to finish it and repaint some parts that needs to be painted.

 

[justlead1]

Hi Whpes what the latest on this one?

 

[WHPES]

Will be doing it starting in June, when my joiner friend is available. We have estimated at 1 week to 1 fortnight depending on the timber condition. The canopy was redecorated last year so it's just touching up on that.

Because of the use of the hotel, we are restricted when we can make noise, so we intend to start early so we are not doing lead dressing and joinery during the wedding receptions!

PS I have ordered a Braithwaite 2000l GRP cistern for the same premises I am going to fit in April re my other post. Will post some photos of the job.

 

[justlead1]

Hi Whpes. I have had a similar situation on a lead roof. Owing to the exposure (on coast) rather than using stheets / tarps to avoid more problem. The tempary fix was to weld the over cloak to the under cloak on the offending bays. Good Luck

 

[WHPES]

I just did a temporary fix with Lead Mate. The tarp is for when we have the timbers exposed.

I'm currently quoting for a lead bay roof on a new build. Don't come across them often on new houses.

 

[justlead1]

Hi. We have found a big increase in new work over the last 10 years. Sold on the basis that lead sheet will last 100 years or more compared to felt at say 15 years. Our rates are only 50 percent greater than felt prices.