I am looking to better insulate my parent’s 1970’s chalet bungalow as the upstairs is noticeably warmer than the downstairs. The upstairs also gets very hot in summer and cold at night and the living room downstairs can be very cold in the winter. The living room has large windows and two and a half of the walls are exterior walls, but I hope insulating above will help it retain more heat. I’m not in a position to be redecorating apart from perhaps removing part of the ceiling in the hallway cupboards, to gain access to the flat roof to push insulation into it.
There is cavity wall insulation and what appears to be the original fibreglass. The fibreglass, (shown in green), is about 60mm thick. The loft insulation is patchy in places and on the angled roof sections it is pushed up against the roofing felt and has no air gap at either the bottom where it meets the bricks or the top where it reaches the loft. At the top of the angled section near the loft, the fibreglass has turned black, presumably due to moisture making its way from the crawl space up into the loft. I can't see any evidence of mould or moisture on the joists.
Both the loft and crawl spaces are used for storage. There is airflow inside the crawl space coming from behind a row of bricks where the soffit is out of view. The crawl spaces have bits of plastic sheet and old carpet nailed against the angled roof to reduce the dust coming from the fibreglass. The gap along the roof between the crawl space and the loft (shown in yellow) is 85mm at its narrowest due to battens used to attach plasterboard and is currently stuffed full of fibreglass with no airflow gap.
I plan to add more insulation on the loft floor (shown in light blue), insulate behind the knee walls (red), the gap below the knee wall to stop drafts under the floor and downstairs light fittings (pink), the crawl space floor and downstairs flat roof (purple), the gap between crawl space and loft, leaving an airflow gap between the roofing felt (yellow), and possibly the rest of the living room ceiling (orange) by pushing insulation into it from the crawlspace.
Regarding the pink areas, once this has effectively been sealed with insulation stuffed into it, the orange area will no longer benefit from airflow from the crawl spaces. Will moisture from the kitchen and bathroom downstairs be able to pass through this area without collecting and rotting the floor joists? The upstairs has chipboard floorboards with one bedroom having laminate flooring and the other and the toilet a single piece of vinyl flooring each.
I’m not sure what type of insulation I should use for each area. My understanding is that the rigid foam board type is tricky to fit in between joists and the inevitable gaps will affect the insulation properties. Please let me know if my plan meets the principles of insulation and which types of insulation to use in each area.
