Insulating in angle between wall and ceiling

Second Captain

Hi,
Several of the properties I've viewed over the last few weeks are older, small dwellings where it seems to be commonplace to have the underside of the pitched roof impinge on what would be the right-angle join between celing and outer wall creating a small angled section. (The third picture in this Daft ad illustrates the arrangement if I have not described it clearly).
Such properties also generally have poor insulation ratings and will need work in this department.

My queestion is does the angled section present a particular challenge in these cases with the risk of a cold bridge (if I understand the term correctly - its all new to me) being formed if the wall insulatiion and roof insulation solutions are not chosen carefully to be compatible? Is the angled section treated as part of the roof or part of the wall for insulation purposes? Does the situation favour internal or external insulation one way or the other?


Bonus question - does any heat insulation solution generally provide better sound insulation than others on party walls?


Any obsevations and pointers welcome.

A fella called fish

Hi,

The roof is a raised collar timber roof. Given the type and age of the structure I would be very surprised if there is any insulation in the walls - so the issue of compatibility with roof insulation is non existant.

The roof probably (in my experience) has a poor quality quilt of rockwool insulation so you may wish to add extra to beef it up to 300mm. You can however roll it down into the sloped section once you're not disrupting the ventilation.

If you're not suitably qualified ask an architect to look over the house before you buy - but be prepared to spend money on external wall insulation (or heating!)

sydthebeat

thats a typical detail for some older dwellings.

what i suggest as a diy ventilation measure is to cut strips of 40mm wavin pipes and push do the slope between every rafter. That way you can fill the gap with insulation while retaining ventilation.

DOCARCH

One to watch when looking at this type of house is to check whether or not the eaves are concrete or timber. Concrete eaves are not uncommon in older (ex corporation) houses.

If the eaves are concrete, you can still insulate the sloped section of ceiling, generally as noted above (to maintain ventilation), plus maybe the addition of a thermal lining board to the underside, and the attic as standard (again maintaining ventilation), but with regard to the insulating the external walls, if there are concrete eaves, this may dictate the use of internal wall insulation to avoid a significant cold bridge (unless you want to go to the expense of removing the concrete eaves all round the house).

If eaves are timber (open) you can isulate sloped section of ceiling and attic and you then have the option of internal or external wall insulation.

Second Captain

Thanks for the replies; they are reassuring. Basically, I take it the survey to be undertaken if I did put in an offer on such property should indicate the exact nature of the construction and a professional will be able to recommend appropriate options from there but it should not be a show stopper to bring the house up to something approaching modern insulation standards.

Anyone want to have a go at the bonus question?

muffler

Second Captain wrote: »

Anyone want to have a go at the bonus question?

5 dolla and me luv you long time