The insulation project… a year later

A year ago I wrote about the insulation challenges facing our new house.

Since then we have spent a lot of money on improving the property. The cavity walls we have were much disputed and one guy did put a camera into the wall and found a cavity but said they wouldn’t be happy to fill the cavity with insulating material because the cavity looked like it was bridging in places.

Anyway, we replaced all the windows recently (more about that in another post soon) and I can tell you that we definitely do have a cavity, albeit narrow, having seen it for myself when the old window frames were taken out. It looks like cavity insulation will not be possible however, based on their previous comments.

We have now insulated the roof space, which was a very tricky job. The roof timbers come down into the top of the external walls at floor level of the 1st floor, so the entire first floor is "in the eaves". The remaining 50% or so of the surface area of the ceiling space on the 1st floor was flat ceiling that could be easily insulated in the loft. Last winter these rooms were seriously cold – when it was sub 5C outside you could feel cold air pouring down on your face at night from the eaves, which lets face it was like living in a shed – the part of the room covered by the eaves consisted of circa 8mm plasterboard, an air gap of around 100mm about 1mm of felt, and about 10mm of concrete roof tile – with air circulating in there.

We didn’t want to pull the ceilings down to insulate, and taking the roof off was a major project. We only had 100mm or so void between the roof timbers, but luckily almost all of them had storage cupboards at the edges of the rooms. So what we did was get some brave masochists to climb into these tiny cupboards and push 50mm thick Celotex foil-backed phenolic insulation boards up towards the apex of the roof until they hit the perlins (timbers that run perpendicular to the roof timbers.

This was no mean feat, requiring measuring and cutting a great many slices of Celotex boarding and forcing them up one after another as they had to be a snug fit and the small cupboards did not allow full length pieces to be cut, so each pair of rafters needed three or more chunks of celotex cut to fit. We also had to cut a new opening into one of the stud walls in one room, to create a new cupboard on that side of the room so this process could be carried out on both sides of the room. Not such a bad thing given that we have gained a storage cupboard.

Finally in the loft void, which we had already discounted as storage space (if you’re going to put it in the loft… you probably don’t need it so freecycle it!), we laid 50mm Thermafleece batts between the rafters up to the exposed edges of the celotex boards that came up to the perlins, then dumped about 20cm Warmcel paper insulation on there, and then covered that all over with another layer of 50mm Thermafleece batts. This wool-paper mush-wool sandwich was used to contain the Warmcel paper insulation which could blow around and cause a lot of mess when the wind blows a lot outside.

All in all it took two guys about 2 weeks to do this work – they also put celotex in the vertical stud walls of the cupboards – for a total of 4 under-eaves cupboards – and nailed plasterboard over everything to tidy it up and reduce drafts. So including materials and VAT (ARGH! Why is there VAT on domestic insulation materials?) it was pretty expensive.

However, it has made a huge difference to the 1st floor. We’ve had some pretty hard frosts already and the house is nothing like as cold as it was last year. It’s not warm all the time, but it definitely isn’t freezing – now the main source of cold is air leakage into the 1st floor floor space, coming up through the gaps in the floorboards, an altogether different problem…

For Scott Vlaminck

Scott from refactr.com commented on my complaint about the Apple OS X weather widget being useless here in the UK and wanted to see the OS X widget showing Cardiff alongside the BBC widget showing Cardiff, and BBC showing Stroud.

Rather amusing it is too today… just how do Apple/AccuWeather whoever it is manage to get a -9C temp for Cardiff today? Ice age we don’t know about yet? Also notice how the weather conditions for Cardiff from Apple vs BBC are completely different. I know which ones I’d trust…

Come on Apple, this is embarrassing! The funny bit is that my iPhone which uses the apple widget setup for Cardiff (as previously mentioned cannot enter my actual town as a location)… and shows the weather there as Thursday 2C then 6C, 8C, 8C, 9C, 7C compared with the desktop mac’s 5C, 11C, 16C, 18C, 18C for the same period! Madness. A minimum of -11C today?

Brain death. Amazing that nobody from Apple UK has flagged this up to the US developers!