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Dormer Bungalow - Little/No Insulation in Crawl Space/Knee Walls

  • 01-10-2012 12:24pm
    Registered Users Posts: 14 ✭✭✭ bunty

    Hi All, hope this is in the correct forum. We recently opened up the crawl space in our dormer bungalow behind one of the bedrooms (we had no hatches on one side of the dormer at all) to put in some wiring and low and behold we found that there is no insulation on the back of the knee walls anywhere, only plasterboard with a foil backing! We also found that the floor of the crawl space has only 100mm fiberglass on it (going by the plans on house minimum was supposed to be 150mm at build - 10 years ago).

    I thought I was going to be blown over with the wind coming from the soffits below so no wondering the bedrooms draughty and cold in winter and sweltering in summer time!. There is also fiberglass sandwiched between the rafters on the slopped ceiling, does not look like there much ventilation travelling up to the attic space above. Some pics below:

    Back of knee wall/dormer window
    Gap out to the soffit
    Gaps going in under the bedroom floor
    Back of sloped ceiling, not much ventilation space by the look of it.

    So, our budget isn't great so we are looking for the best way to get some more insulation and airtightness. Access is very limited. The joists are 360mm apart and 220mm deep on floor space and 360mm apart and 100mm deep on the knee wall.

    Any recommendations on how we could get this sorted out would be super helpful.



  • Registered Users Posts: 3 dinkybell

    Hi there what about those space blankets from homebase to top up the floor part of the crawl space, get 200mm and lay on top of existing fiberglass. Bring it right up to the edge of roof rafters so as to leave a ventilation area but stop the wind blowing in towards the back of walls. Also right against the wall to block air traveling under bedroom floors.

    Not sure what to recommend for the slopes, doesn't look like much ventilation space with the fiberglass rammed in there. As for the back of the knee walls not sure either I'm afraid.

  • Registered Users Posts: 3 dinkybell