Flat Roof refurb Help please

bobsa1

HI, our house was built in 1936 as a flat roof modernist property and despite lots of extensions and character changes over the years, the flat roof remains. When we moved in twelve years ago we had the deck of the roof replaced then new covering (think it was bitumen but not sure).

The roof has always been a problem, leaks through the parapet etc and very very poor insulation.

The bad rain over the past few days have identified a leak so the time has come that we need to do something.

I've spent hours looking on websites and it appears that we can keep the existing cover as a vapour barrier (swept clean first) then cover with kingspan type insulation and then put a rubber covering on.

Looking at some websites it appears that this can be done by a competent DIY'er and to be honest whilst we need to get this done money is very tight!

The DIY rubber coating is firestone and works out quite a reasonable price from a company that specialise in DIY supply but the kingspan appears to cost a fortune. Has anyone got knowledge of a Kingspan alternative or can you suggest anything else?

Many thanks:beer:

slipperyshoe

Kingspan is one of the best producers of PIR insulation. As a domestic customer I would personally only get from them or from Recticell. Cellotex and other brands are available but the quality of the board is questionnable.

I would suggest that you do not believe the hype regarding EPDM systems but each to their own. I have posted many times on comparing different flat roof systems so if you check my previous posts then you will find some info.

slipperyshoe

Regarding retaining existing, it is possible but it would be a vapour check (only metal lined materials are a vapour barrier). If you know the build up of the existing then kingspan technical be able to do a condensation and U-value calculation for you. It is worth doing this (free). Just one tip, if they ask 'are you an architect?' then say 'yes'!

ed110220

slipperyshoe wrote: »

Kingspan is one of the best producers of PIR insulation. As a domestic customer I would personally only get from them or from Recticell. Cellotex and other brands are available but the quality of the board is questionnable.

I would suggest that you do not believe the hype regarding EPDM systems but each to their own. I have posted many times on comparing different flat roof systems so if you check my previous posts then you will find some info.

What makes you say the quality of Celotex is questionable? I've used it and Kingspan interchangeably depending on which was available/cheaper at the time and never noticed any difference, but of course I never did any tests.

If you need a large quantity, it can be cheaper buying seconds (boards with slight damage). I never bought enough at once to make the delivery charge worthwhile (only bought two or three 1200x2400mm sheets at a time).

cyclonebri1

I was just wondering how many times this roof has been recovered, and if the previous coating have been removed or simply gone over?

This stuff is heavy and it's not unknown for the weight of many layers of bitumen felt and tar etc, to actually create structural issues.

I just think it would be worth checking the level and flatness before you begin, and at least try to ascertain what is already present before you add more.

Might not be relevant, but ........................;);)

slipperyshoe

ed110220 wrote: »

What makes you say the quality of Celotex is questionable? I've used it and Kingspan interchangeably depending on which was available/cheaper at the time and never noticed any difference, but of course I never did any tests.

If you need a large quantity, it can be cheaper buying seconds (boards with slight damage). I never bought enough at once to make the delivery charge worthwhile (only bought two or three 1200x2400mm sheets at a time).

Celotex boards are shocking quality. It only really shows when you install a tapered (or cut to falls) scheme. Boards have -+3mm tolerence and this (in my opinion) is poor. Boards also often come out warped. Celotex is absolutely fine for EWI or infilling between joists, but I would never use it in a warm roof construction.