Cold to Warm Roof Conversion

securespark · 24 Feb 2020

Couldn't find the original post, but someone on a fastening forum recommends this method.

Block existing ventilation throughout

Take out any insulation that exists below the deck, keeping it here will create interstitial condensation

Fix PiR insulation over the felt. The felt if in good condition will act as VCL. 120mm will meet your regs

Fit waterproof membrane eg single y membrane

Plasterboard and skim to underside of joists

What does the first point (Block existing ventilation throughout) involve?

Notch7 said:
you need to make sure the insulation is returned downwards at fascia and brickwork to remove any thermal bridging.

I've been looking for diagrams of this, but can't find any.

I'm sorry to be a PIA, but I don't know much about roofing, but want to try and get enough knowledge so I get the best possible outcome.

securespark · 30 Apr 2020

We have found another roofer and will give up the idea of going back to the original roofer.

I'd like to post some pix and ask for advice please.

Picture 1: There are three joist ends like this which the roofer promised to replace, but didn't. Should they be?

Picture 2: Some of the flat roof has proper firrings,

Picture 3: while other areas dont. Should these tatty bits of wood be replaced with the real thing?

Picture 4: There is a disused flue from an old wall-mounted gas heater. Can this be bricked up without the need for an airbrick?

Picture 5: This is the area above the "fireplace".

Picture 6: There is a (loose) piece of timber in place of some bricks on which a joist is resting. Should this be replaced with brick?

Picture 7: Over the doorway, there is a steel holding up the inner leaf, on which the joists are resting. Should this be replaced with a Catnic?

Picture 8: Old cast stack in the corner of the room. I want to replace with PVC and fit new flashing above. The nearby pipe run to the en-suite loo is horizontal at best, so needs replacing with a better drop. Are fittings and pipes interchangeable?

Picture 9: Twisted joist. Do these need replacing or tying down?

Cheers people!

securespark · 30 Apr 2020

Forgot to say we want the existing flat roof converted to a warm roof and I want to pull up the floor (chip) and fit Celotex under the floor because the room is above an unheated garage.

Mrs Secure thinks this will be a very expensive task with little benefit. I think without it, the room will be very cold in Winter and very hot in Summer.

She thinks insulated underlay is equally good.

securespark · 1 May 2020

https://www.underlay4u.co.uk/blog/2018/05/10/best-insulated-underlay/

I'm not convinced!

It says "As well as keeping your home that little bit warmer, the Midas 12mm also has great sound insulation."

securespark · 2 May 2020

Will have a chat with the new roofer about it, see what he reckons.

securespark · 3 May 2020

The surveyor said that the rotten joist ends are not structural, but would you repair them anyway or is it a pointless task?

And should the roof joists be tied to the walls?

securespark · 1 Jun 2020

Seen a roofer tonight who will quote for a warm roof. He will take off the EDPM and replace it with a breathable covering as he says the rubber will sweat. Then he will put Kingspan on top, another deck and another layer of breathable membrane.
He said he will put mushroom vents in.
Now I'm confused.....I thought you didn't need mushroom vents in a warm roof...in fact, I thought you didn't want holes in the insulation.
Could someone explain, please?

securespark · 15 Jun 2020

Spoke to a different roofer. I said I wanted a warm roof. He said you still need mushroom vents.

I am now thoroughly confused and don't know which way is up!

His quote stated the following:

ESTIMATE

Work to Roof Area 24m2

• Strip the existing rubber roof covering
• Replace three end joists
• Re insulate the roof area 24m2
• Re board the roof area with 18mm interlocking boards 24m2
• Install a new GRP trim to the roof perimeter
• Lay a new Sika Liquid Plastic Roof System
• Remove the rear tiles, flash and re secure
• Replace lead slate
• Install four mushroom vents
• Remove debris

What do you make of that?

securespark · 15 Jun 2020

Having had a bad job done once, I need to make sure this roof is sorted once and for all. Either these roofers don't understand that I want a warm roof, or I have misunderstood what a warm roof is.

securespark · 20 Jun 2020

Mod, could you please move this to roofing for me and leave a copy here.

Thanks.

securespark · 1 Oct 2020

Finally got a roofer to make a start, but I am an eternal worrier.

The guy has sistered the rotten joists with new short pieces.

He has replaced the L shaped steel over the bedroom door with something that looks more suited to the job, but the inner leaf is still resting on the door casing.

He says there is no need to separate the main pitched roof loft space from the flat roof. Surely if it is not separated, the heat in the extension (with the warm roof) will just find its way into the loft - we will be effectively paying to heat the loft, surely?

MOD: securespark, in future could you please post questions in the correct forum, you've been on the fora for over 16 years, so I'm sure you will be able to navigate and post in the correct forum in future. Thanks in advance.

securespark · 1 Oct 2020

To be fair, I asked ages ago for it to be moved and it wasn't.

The other issue is that often the footfall in GD is much bigger than the other fora and you are more likely to get a response.

I have noticed others post to GD because they don't get a reply in the "correct" forum.

MOD: Please note rule 10 of the forum rules. I note in June you asked in the thread for the post to be moved, it's very unlikely any of us would see that. Please use the report facility.

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Cold to Warm Roof Conversion

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