Insulation Worries. Dormer Ceiling.

Aeneas

While upgrading the insulation in my dormer bungalow I discovered that the builder has put fibre glass in the space between the angle of the ceiling and the roof. This is the angled portion of the ceiling that runs between the top of the bedroom walls and the flat ceiling in the centre of the room. The studded walls are five feet high and the angled section is about four feet from the top of the wall to the flat part of the ceiling. On this angled section the distance between the ceiling plaster and the outside slates/felt is about 6to 8ins. Below the angled section are well ventilated eaves and above them a well ventilated attic. The builder has stuffed fibre glass into the 6-8in space between the ceiling and the felt. I see from Dept Environment guidelines that builders are supposed to leave a 50mm space between the insulation and the roof at this point. Should I be concerned about this? Or is it another example of common building practice that differs from the regulations and causes no actual harm?

renedescartes

Hi Aeneas,
I have exactly the same problem. I have been looking on the web and I came across a product in the states where they have a plastic sheet9 they call it a batt) that is stapled in the area and then they pump insulation(recycled newsprint) into the gap thereby allowing a ventilation space for air to circulate. It does appear that there is a very real need for air circulation. If you are interested I will try and re-locate where I saw this.
I have the very same construction in my house and I am at present trying to locate how I can the correct materieal to insulate the sloping space. Also I have 3 dormer windows that are not insulated which I am trying to have insulated. Again in the States they pump the same material in through the plaster board from the inside through 25mm holes (no mess). In the states this is a DIY job but I cant so far get anyone to do it. Those that i have spoken to so far said thet the boards would have to come down. Since you have been down this road I would appreciate any help

Michael

Aeneas

Thanks. For my roof I think I will leave the insulation as it is unless someone answers my questions above showing that it is a real problem. For insulating dormer windows I have outlined what I have done under the thread "heating in our home".

Mellor

Aeneas, if the space was fully filled then it is a problem. A 50mm gap is required.
how much insulation was put in, is it possible that the gap is 8 inches and the builder put in 6 inches, this is fine,

it is also a possibikity that he used a breathable roofing felt, if so the gap isn't required, but this felts aren't too common, but are becoming more popular. try find out the name of the felt installed

fatchance

doing a new house atm and i'm putting 100mm dense fiberglass wool in there and on the underside i have to use kingspans wt56 plasterboard insulated sheets in order to meet building regs for dormer insulation. my rafters are 6" so all that i can put in thee is 100mm cus 50mm is needed under the slates for air movement