Shared Flat Roof - Temporary Repair

[wytco0]

I have a town house with a flat roof and the 3 layer felt roof is shared with the adjoining house, it was last replaced 20 years ago. We have a few small leaks on our side but our neighbour says his does not leak at all and he is not interested in replacing his half of the roof.

As our neighbour is selling his house I am looking for products to repair our side or the roof and which will last for a year or two.

Can anyone suggest a product or technique for this? I know this is not the best solution but I want to ensure we are leak free over the winter.

If we end up have to replace our side of the roof without the neighbour doing his at the same time is it possible to join our replaced half to his old bit?

Thanks.

 

[breezer]

tarpaulin? "sticky plaster" (available from builders merchant)

 

[Thermo]

cant think of the name of it, but you can buy large tubs of a flat roofing repair compound. It basically goes on with a brush, is black and horrible, but dries out and is very good. It can then be covered over with chippings. If the name comes to me ill let you know!


Thermo

 

[comms]

The black sticky stuff THERMO is on about is called roof seal made by thompsons, alternitavly you could use self adhesive weather banding this comes is differing sizes & a roll of it costs about £30.

 

[Thermo]

comms, close but its not roofseal, its the big quantity stuff comes in a big black tub about 25 litres in size. ill find the name out for you

 

[wytco0]

Thermo, if you can find the name of that stuff it would be great. I had a look at the Thompsons stuff and it only seems to come in 5L cans.

 

[masona]

I think Thermo mean synthaprufe ???

Good stuff, strong smell though and you can buy it in 25 litres drum

See this

 

[wytco0]

masona, thanks for that info however looking at that product it does not seem to be recomended for roofing work, have you used it on top of felt roofing?

 

[Thermo]

I cant think of the bloomin name, but its a synthapruf equivalent just a bit cheaper. Synthapruf will do fine or aquaseal is another branded one i can think of. Get it from a builders merchant, it will be cheaper. buy a cheap broom to apply it with, wear old clothes you can throw away and have plenty of pairs of rubber gloves to hand when you do it

 

[masona]

masona, thanks for that info however looking at that product it does not seem to be recomended for roofing work, have you used it on top of felt roofing?

Yes, sorry I gave you the wrong link, you can get Synthaprufe Waterproofer for flat roof repairs, long time since I have done one, maybe they change the name as well. You could give them a ring, I know they are not cheap.

 

[wytco0]

I have been up on the roof today and I cant find any obvious holes, however the parapet around the edge of the house certainly has some wet bits under the capping stones, I will get the cap stones re-bedded and any faulty mortar replaced.

I spent several hours brushing the gravel from the roof and also hosed the roof a bit to see if there is any pooling and there is ! The gravel is very dirty and there is a fair bit of mud in it I guess from standing water?

So my plan is :-
1) Take of as much gravel as possible and wash it.
2) Wash away as much of the mud and moss of as I can
3) Paint FLEXACRYL on the exposed felt anywhere that I see any possible faults.
4) Let the Flexacryl dry and then replace gravel

Does this sound OK?

Also does anyone know where I can get Flexacryl in amounts larger than 5L? The builders centre only has 5L cans and I need about 15-20L, as its very expensive it might be a lot cheaper to get 25L

 

[masona]

Also does anyone know where I can get Flexacryl in amounts larger than 5L? The builders centre only has 5L cans and I need about 15-20L, as its very expensive it might be a lot cheaper to get 25L

You can only buy Flexacryl in weight by kg and the biggest they do is 20kg. The reason it's sold by the weight is because of the density of the temperature increase in volume when it's the same weight, it's the same with bitumen materials ! Right that's the boring bit out of the way.
See this for Flexacryl.
You can buy synthaprute for roofing but cost £99 for 25 litres !! See here

the parapet around the edge of the house certainly has some wet bits under the capping stones, I will get the cap stones re-bedded and any faulty mortar replaced.

I would do this first and see if it has stopped the leak as you say you cannot see any cracks on the flat roof yet, so don't go and waste your money yet. A lot of people make a mistake thinking the leak on the floor is in line with the roof and could be 10' away from it!

 

[Oskool]

Also does anyone know where I can get Flexacryl in amounts larger than 5L? The builders centre only has 5L cans and I need about 15-20L, as its very expensive it might be a lot cheaper to get 25L

As masona said if you decide to waterproof the roof, Flexacryl only comes in 5kg & 20kg, another alternative would be Acrypol, it is better at waterproofing because it comtains fibres but takes a little longer to apply, the Flexacryl is a little creamier.
Both are about the same price but you will still be looking to pay £120-150 + vat for the 20kg which will cover approx. 10-20m2.

If you want a cheaper product try Rufabrush or All Weather Brush which is a black bitumen based waterproofer, look to pay £20-30 & £30-40 + vat for a 25ltr covering 25m2.
You can get all these from the roofing merchant, Asphaltic (www.asphaltic.co.uk) which has branches all over the country.

 

[wytco0]

OK a progress report, I have replaced some of the parapet brickwork, there were 3 courses in one corner which were wet and where the mortar seemed to consist of wet sand! The mortar under the cap stones above them was broken up and there was no DPC in the capstone mortar bed, I understand there should be a DPC bridging the whole wall (outer, cavity and inner) under the stones.. The total parapet wall is about 15 Metres long but I have only replace 3 meters.

I am now going to lift all the remaining cap stones and at least replace the capstone mortar and put in a DPC. I am hoping that I don't need to have any more of the parapet wall rebuilt!

I also have a bit of a problem, I would like to avoid the Flexacryl treatment if possible as its so expensive. However I only have another couple of weeks with the scaffolding and as it could now be cold and wet for several months I need to decide whether to use it before I have had time to see in the parapet repairs have cured the problems.

Any further advice ?

 

[masona]

I also have a bit of a problem, I would like to avoid the Flexacryl treatment if possible as its so expensive. However I only have another couple of weeks with the scaffolding and as it could now be cold and wet for several months I need to decide whether to use it before I have had time to see in the parapet repairs have cured the problems.

Any further advice ?

A garden hose and wet the roof as much as you can should tell you something. Do the flat roof area first.