Botched join between flat roof and main roof

crystaltips_68

iamcornholio wrote: »

The presence of expanding foam to the main roof, and whether the contractor looked at this prior to quoting is irrelevent.

The junction of a flat and pitched roof is a standard and easy detail, and the contractor should do the work properly - foam or not.

The job done is unsatisfactory and not acceptable at all.

What should be done is

approx 500mm of the pitched roof tiles are removed
(insulation inserted betweent the rafters to replace the foam which comes off with the tiles)
some plyboard fixed to the top of the pitched roof rafters
a layer of breather membrane (or felt) laid on this
the new flat roof cover is then taken up the pitched roof to cover the plyboard and over a lath to prevent water being blown up under the tiles

Then the tiles are replaced on laths, to form a nice straight edge

Its clear that the contractors who did the work have not got a clue abour flat/pitched roof junctions

I dont really understand the technical bits of this, ie where does the plyboard get fixed? Right at the top of the roof? What is a lath? But thanks for the advice. I will try to tell the company that did the work. Trouble is, they should surely be able to work this out for themselves? They are NFRC's so should know, especially as the boss is a roofing teacher!

Have you worked with a spray foamed roof before, iamcornholio? Where do you live? Please feel free to come and mend my roof!!:T

crystaltips_68

baldelectrician wrote: »

I know a couple of roofers, the general consensus from them is to steer clear of foamed roofs

Neither would have touched it

Did you get any others round to quote?

Am awaiting one quote and have another coming for a look tomorrow.

crystaltips_68

Just so you have the full story, here is a link to the 'quote' thread.

http://forums.moneysavingexpert.com/showthread.html?t=2251341

iamcornholio

Basically, the flat roof is taken part way (about 500mm) up the pitched roof and under the tiles.

The plywood is put on top of the pitched roof rafters just like it is currently on your flat roof joists, felted, and then the tiles put back on to cover the join up. Laths are the bits of wood which the tiles are fixed to

The problem with this arrangement is not rain getting through the tiles, but rain being blown up under the tiles where they meet the flat roof. So the contractor should pay attention here.

If this junction is not done correctly, unless penetrating water is obvious and visible from the inside, then it tends to go unnoticed and leads to rot of the timber quite quickly

If you get stuck, I can upload a detail of how it should be done. But really, a competant contractor should know

crystaltips_68

Thanks Iamcornholio, but i think the problem is more to do with not being able to remove the original tiles without removing the whole row/column. The spray foam has welded them all together to make a continuous structure, so if one comes off they all come off, well, not without making a mess. Would your solution overcome this?

iamcornholio

The tiles can be taken off, and the foam can be scraped off, or removed with a solvent. Whole rows of tiles, the length of the flat roof have to come off. If the tiles are broken or not possible to clean off (ie are they asbestos like the others? ), then they just get binned and new ones fitted

It will be a be a bit awkward messing about with the last row of tiles and scraping the foam off from behind them, buts its certainly do-able

I'm not sure why the tiles were foamed in the first place, but if new ones are put back, then a layer of felt/breather membrane is put back instead of the foam

Incidentally, that foam concept is a really bad idea and should be avoided at all costs. Apart from problems with maintenance such as this, its known to cause rot of timber rafters. Those companies that do the work set up, wind up and re-appear in another name with alarming frequency. And just try claiming on their 20-30 year guarantee. Nightmare

crystaltips_68

iamcornholio wrote: »

The tiles can be taken off, and the foam can be scraped off, or removed with a solvent. Whole rows of tiles, the length of the flat roof have to come off. If the tiles are broken or not possible to clean off (ie are they asbestos like the others? ), then they just get binned and new ones fitted

It will be a be a bit awkward messing about with the last row of tiles and scraping the foam off from behind them, buts its certainly do-able

I'm not sure why the tiles were foamed in the first place, but if new ones are put back, then a layer of felt/breather membrane is put back instead of the foam

Incidentally, that foam concept is a really bad idea and should be avoided at all costs. Apart from problems with maintenance such as this, its known to cause rot of timber rafters. Those companies that do the work set up, wind up and re-appear in another name with alarming frequency. And just try claiming on their 20-30 year guarantee. Nightmare

Yes, the foam is a nightmare. The previous owners put it on to supposedly extend the life of the roof.
As for taking it off, the contractor tried to get some off but it took ages to do about a square foot. Thats what he said anyway. I suspect when i withold money they will be back to continue taking the foam off.

crystaltips_68

Just to let you all know; i am sending off a part-cheque today. I am witholding £500. Will let you know the outcome!:)

crystaltips_68

Just to let you know; they came and took a load of the spray foam off today and patched the roof, but only after i with-held £500!

Sorted now though!:beer: