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Loft Conversion

Reroofing and upgrading insulation in 40 year old loft conversion

Anonymous user 09/03/2024 - 3.19 PM

We have a house with a double dormer loft room build in 1983. It was built to specification at the time (I have the hand drawn plans and building regs certificate). It is well built i.e. has steels and correct floor joist etc. The issue is it's cold in winter and very warm in summer. The plans show that it has only 100mm of fibre glass in ceiling joists (150mm joists) and 75mm of fibreglass in the dormer cheeks (75mm joists). The flat roof part is a cold roof with 50mm cross-ventilation. The whole roof is near end of life and needs replacing. What is my best option to get a habitable room i can use as a child's bedroom? a) Hire a roofer to do the roof work, while asking a builder to removing plasterboard from inside and take out old fibre glass and replace with correct amount of PIR and replaster? b) try to reinsulate with PIR from outside and leave current plaster board? Perhaps installing hybrid/warm roof? c) leave internal insulation and plaster board and try and insulate over it internally with PIR? d) hire a loft specialist and architect and partially rebuild to meet full Building control requirements? cheers Phil.

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4 Answers

Anonymous user

I would certainly say if it’s going to be a long term well used room for a child I would recommend upgrading it to the new building standards having an architect draw up Amendments required and using the new correct insulation with the correct king span slate or tile ventilation and possibly upgrading the windows to the new uv values

Answered23 February 2021

Anonymous user

You can leave the plasterboards there to save money,fix isotherm insulation over the top it's only about 3mm thick, overboard it and skim it, save a lot of time,mess and money

Answered25 February 2021

Corsham loft conversions

Rating: 5 out of 5

Corsham

While the reroof is taking place there a specific insulation we use in loft conversion called actis Hybris high goes in between the rafters and then also trioso super ten which could go over the top of the rafters and then batten then felt and then counter batten and this wold bring you up to the current building regulation requirements without stripping the plasterboard from the inside. Thanks Jon.

Answered6 March 2021

Anonymous user

Nowadays a hard insulation is used ie. celotex or equivalent. Normally 100mm between joists but allowing air to flow above that usually between 30-50mm depending on joist size. Then you add another 25-30mm below the ceiling joists before plastering. It’s called a warm roof system and it does work. However, the air needs to flow above insulation so either a breathable roof membrane or vented soffits. Hope this helps

Answered11 March 2021