DIY Doctor

Vapour Control Layer - Missing - Any Solutions? for Membrane Roof?

Postby afzalg2k » Fri Mar 27, 2020 3:03 pm

Hey All,

I am no expert, instead i got a roofer in to have a look at a Flat roof that we go installed 5 years ago - it was a Membrane Roof - however it started bubbling.. and is leaking.

Had a bunch of roofers down, but very few knew much and kept advising me to change it to a felt roof etc.. Anyway finally found a roofer who sounds great - seems to know what he's talking about..

Anyway it started off as a 'repair', then after inspection, it came to a new Membrane roof.. However he was pulling back and he could not understand why it was so bad everywhere - anyway. He said he called SPRA and they told him to do a 'core sample'. Apparently he states as its a hot roof, it needs to have a VCL Layer, and apparently ours doesnt.

So hes said:
What’s now involved is complete removal of the old membrane, all the old decking insulation and decking beneath the insulation. Dispose of accordingly, supply and fit new decking to the joists fixing with 50mm screws. Supply and install vapour control layer to this part of the roof.
Supply and install TR27 fit for purpose insulation to complete roof area. We would then install a further 3/4 inch plywood using PU adhesive as you cannot penetrate the newly installed vapour control layer. Supply and lay EPDM single ply membrane using fully adhered method. Using purpose made trims to all perimeter brickwork and fit for purpose drip edge where ever needed.

Its now going to cost me 6k! (From originally £800!)..

I was wondering if someone can tell me:
1) Does this sound right?
2) if there is no VCL layer? is there any way of putting it on without having to redo the whole roof?
3) Anything else you can advise?

Many thanks

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Postby stoneyboy » Fri Mar 27, 2020 6:55 pm

Hi afzalg2k,
What your roofer is suggesting is probably right if you want to have a warm roof and an EPDM covering. From what you say it sounds like the roof deck will need replacing but this needs confirming (it should not have deteriorated badly in 5 years unless chipboard has been used).
An alternative would be to insulate below the roof structure, add a VCL, board over and re-plaster. The roof would then become a cold roof and would have to be cross-ventilated. You would have to allow for the ceiling to be about 150mm lower unless you are prepared to remove the existing ceiling. Treatment of the perimeter where attached to the main building would have to be addressed.
Regards, S
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