Closed job
Air Sealing (and re-insulating) our Ceiling
Job description
34 Lawrence St --- ─ Rachel Margaret 34 Lawrence St, Newtown, Wellington, 6021 Overview We want to make a real difference to the performance of the building envelope at 34 Lawrence St. Dumping more insulation in the ceiling isn’t the answer. Controlling air movement better is. Background The property is a 1906 roll porch villa that was renovated in 2014. The ceiling area that is in scope is ~120m2. The house is 40m from the road/car pad. Goals Airseal the ceiling and floor. By limiting the movement of hot air from the house into the ceiling we maximise the Rvalue of the insulation in the ceiling and floor 1. Upgrade the insulation in the ceiling, its long overdue and under-insulated. 2. Upgrade the insulation under the floor. On the same basis controlling the movement of air into building thru the floor is required. Specifications Renew the existing loft. We need to replace the current batt insulation with something that can be made airtight and maximum Rvalue. Remove the existing rafter insulation (batt with building membrane stapled to the rafters) Take up the loft floor and remove all the batt insulation below that so we can start again. Seal all ceiling penetrations under the loft floor with foam. Add additional 1200mm to the loft floor width Insulate below the loft floor with 90mm foil faced eps layer in the joist bay All edges foam sealed to stop air movement Insulation the rafter bay above the loft deck 1 layer of 90mm of foil faced eps in the rafter bay 1 90mm layer eps perpendicular over that. All edges foam sealed to airseal the board at the rafters Replace the sides of the loft with eps board (again to stop air movement) All layers foam sealed at all edges Add a opening in 1 side to allow access to the ceiling from the loft (nothing fancy, a section of eps that can be removed (friction fit)) Remove the existing ceiling insulation Currently there’s 100 years of rubbish, then a layer of blown raw wool installed in 2000s, with 200mm of polyester blanket over that Roll up the polyester to reuse (is this a good idea?) Remove the remaining wool and rubbish to get us to a clean ceiling Air Seal the Ceiling This is the important bit. Foam seal all the penetrations into the ceiling to control the movement of air out of the house. In particular: All wall / ceiling intersections Wire penetrations The old chimney (kitchen vent) The gable end and eaves Install new ceiling insulation 500mm of Blown Cellulose (or wool) --- across the ceiling space. Reinstate the polyester blanket insulation (is this worth bothering with?). Air Seal and insulate the floor Approx ½ the accessible floor has eps board insulation. The rest is either fibreglass batt or missing. Replace all the missing, batt / foil insulation with 90mm foam board insulation (the highest Rvalue we can) Air seal the entire floor joist area with foam Around the perimeter of all joist bays Around the fire plinth All floor penetrations
