Flat Roof Sealant

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sued51
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Joined: Sun Jan 22, 2017 7:57 pm

Flat Roof Sealant

Post by sued51 »

We need to reseal a flat roof which has caused problems since we moved into the house - mould/damp on the ceilings during the winter. We have done it several times previous (using the same materials and method as our other flat roof which is fine) but it now needs doing again.

We have asked several tradespeople for quotes and they have been to look but as yet none have given us a price for trying to remedy this permanently, so we are looking to just reseal it again ourselves before we get any amount of rain - please can anyone recommend any roofcoat/sealant for this? We do know of several, i.e. Moorelastic etc, but just wondered if anyone had found anything better

Thank You!
Jim B
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Re: Flat Roof Sealant

Post by Jim B »

What you need is a vent installed and the ceiling painted with Fungitex paint. It's lack of ventilation that causes mould.

Jim
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bromerzz
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Re: Flat Roof Sealant

Post by bromerzz »

It never hurts to reseal a flat roof. I do mine every 3 or 4 years in spite of the 10 year guarantees. Very important to prep properly, sweep up any dust , droppings etc and remove any flaky old paint. Ensure you seal round any downpipes in the roof with an Acrylic filler and allow it to dry. Make sure the roof itself is dry. Then roll or brush away.
In fact I redid mine just 3 weeks ago. The roof is 160 m2 and I used a product called Mercola Isocryl PU Hybrid in 10 l drums at approx €60 a drum. Coverage is about 40m per 10l. If you can, give it 2 coats preferably applying the second coat in a different direction from the first.
Used other similar products previously such as Hyperdesmo and another called Vitex Hyroof PU Hybrid.
All water based and much the same, makes sure what you buy has a UV rating.
sued51
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Re: Flat Roof Sealant

Post by sued51 »

Jim B wrote: ↑Wed Nov 06, 2019 12:09 pm
What you need is a vent installed and the ceiling painted with Fungitex paint. It's lack of ventilation that causes mould.

Jim

We have a window open permanently and have done this -the problem is definitely coming in from the roof!
PolemIan
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Location: Polemi

Re: Flat Roof Sealant

Post by PolemIan »

Also recommend hyperdesmo, we used all on the flat roof areas on the complex where we have our apartment. Available from Charalambous Pafou the shop on the main road through Kissonerga. You have to plan your installation quite carefully though as once opened you’ve got 24 hours, 48 if you’re lucky, to use it. It comes in 1, 5 and 25 kg tins. From memory each coat is about .8kg per square metre. 2 coats recommended. I’ve also used it on our house, a small tin to cover a bit of the ridge tiles on the roof and, as it’s also in white, I did the top of our wooden pergola with it at last spring as I was fed up of paint flaking. Worked a treat.

Ian
Jim B
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Re: Flat Roof Sealant

Post by Jim B »

I had a company round to give a price on external insulation and they confirmed that we needed vents as we had mould problems in two of our bedrooms. I said exactly the same about leaving Windows open etc and was told the mould is caused by cold points and condensation. I've lowered and put 100mm of insulation on the ceiling in all the rooms and 50mm on the internal walls of two rooms that had condensation problems which appears to have done the trick. I painted all the walls and ceilings with Fungitex bought from Nikonnikos.
On the flat roof I used an aluminium based paint and never had any problems, I plan to put sheet insulation on the flat roof which hopefully will remove another heat loss area.

Jim
kansas
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Re: Flat Roof Sealant

Post by kansas »

We've just sealed our flat roof with a similar product to which Lloyd is referring, purchase from One Stop. We cleaned the roof thoroughly, applied a thick coat of Deep Seal as undercoat in order to ensure bonding to the original coating, which was a solvent based product, then two coats of the water based PU Hybrid. It went on perfectly and thickly, drying overnight. We haven't had any problems with damp or mould in the house, but it's a good idea to reseal a flat roof every few years.
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PW in Polemi
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Re: Flat Roof Sealant

Post by PW in Polemi »

Hyperdesmo works a treat.
Kay
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sued51
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Re: Flat Roof Sealant

Post by sued51 »

Thank you everyone - looks like Hyperdesmo is the best then
Jim B
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Re: Flat Roof Sealant

Post by Jim B »

Just finished putting 4" air vents in the bathrooms and bedrooms. Put 4" insulation internally on the ceilings, lowered the ceilings using suspended plaster board with 3" of insulation. Painted everywhere with Fungitex and now just the flat roof to paint. Will try Hyperdesmo and then put 4" of insulation on top and coat that with the same. Already the difference is amazing.

Jim
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