A car's worth of insulation

Having resolved our supply chain issues, we brought home a full car load of insulation yesterday. Soon this will be attached to the formerly grotty wall of the children's bedroom, and it should be a much cosier space.

At the builder's merchant, my husband met an NBT representative who talked him through the justification for using conventional plasterboard in conjunction with the Pavadry materials. Apparently it's all in the technical manuals. I understand there's an acronym for that, but he was far too polite to use it.

More solid wall insulation

In addition to having the loft converted into a bedroom, for use by our daughter, we are also upgrading the insulation in the bedroom she currently shares with her brother. This room is on the first floor, and already is insulated externally on one external wall (the side wall of our semi-detached house). However, unlike on our ground floor, there is no solid wall insulation on the other external wall in this room. This cold wall is still prone to condensation and mould in winter.  Which is obviously not what anyone would want in a child's bedroom.

So, we are going to have internal solid wall insulation fitted to the uninsulated cold wall. For this we are going to use 'breathable' materials, as we did for solid wall insulation in the rest of the house (but not the new loft conversion work). This involves us specifying and ordering Pavatex woodfibre boards (Pavadry), plus the fixing and taping materials, so our builders can install them.

This isn't as simple as you would hope, in that the product suppliers (NBT) don't deal directly with individuals, so we have to go through another builders' merchant. There has been some back and forth about which organisation can provide price quotations etc. Hopefully, somebody will take our money at some point, and we will get the products on site, on time.

The product range seems to have moved on since we used earlier versions of this product in 2009/10. For example, it is no longer required that the finishing layer of plaster be lime plaster. Instead it can be finished with standard plasterboard. This makes it easier for conventional builders to install - as most will have no experience with lime plaster. It seems a little odd, since we were persuaded on the lime plaster arguments with the previous product.  However, I haven't got a moisture movement model, or the knowledge to use one, so I am going to assume the manufacturers have done the calculations and that using gypsum plaster / plasterboard will not be detrimental.

In the main loft conversion, all is going well - with work on pause for a few days, until the staircase is installed and the loft room connected to the rest of the house.

Spaceship loft

Work is continuing with the loft conversion. Much of the internal insulation has now been installed. It is made up of two different materials - Xtratherm, a rigid polyurethane foam board, overlain with a silvery space blanket material.

For the ceiling / roof level insulation the builders have installed 100mm of Xtratherm, and 80mm for the 'dormer cheeks' (the side walls of the dormer).

Excitingly, this is very much how the future was meant to look. Less excitingly, this shimmering, spacey look is being covered by plasterboard - which I don't think has ever been accused of looking cool or futuristic.

We are looking into whether we can add extra insulation into the spaces created for fitting the LED lighting. This might be possible if we can specify LEDs which can be surrounded by insulation, or by using lighting covers. The additional insulation isn't part of current practice, or needed to meet building regs, but it would be a good thing to do if possible.

Today we also had a visit from an Energy Performance Certificate (EPC) assessor. In order to get the government payment for generating renewable energy from our PV panels (known as the FiT - Feed In Tariff), it is necessary to have a home which achieves at least D on the EPC scale. We should find out the result in a couple of weeks - according the scheme rules, assessment needs to be delayed until the staircase has been built into the loft room.

Loft conversion

We are currently having our loft space converted into an extra bedroom. Many of the details are just as required by Building Regulations, but we are having higher specification windows and wall insulation. We have chosen triple glazed windows, to improve heat retention. There are two triple-glazed Velux windows, already installed in the sloping roof and two triple-glazed windows for the dormer window on order from a factory in Estonia. Our insulation will be extra thick on the side wall of the house, as that has existing external solid wall insulation, and full internal wall insulation will be installed in addition.

We are also using metal guttering and down pipes rather than standard PVC.

Windows: easy and difficult
Ordering the triple-glazed Velux window was very straightforward. However, specifying and ordering the other windows has been a long and somewhat fraught process, requiring extensive discussions between our builder and the specialist company we used to order the window, as to precise sizings and particularly the fitting system and materials needed for that. Our builder assures us that windows are always difficult because every manufacturer uses a different fixing system, and windows all have different details. Nevertheless, it has brought into sharp focus, yet again, how difficult it can be to specify components which go beyond current standards.

Solar PV
We are also going to have some solar PV fitted to our west-facing roof - as the (smallish) south facing roof already has solar water heating on the higher part, with the remaining roof area being over-shadowed by buildings and trees. We were debating having additional PV panels on a south facing frame on our new flat roof (on top of the new loft dormer). But this would require planning permission, because the highest edge of the frame would be above the existing ridge line - as opposed to putting a full set of panels on the street-facing roof which requires no planning permission. Planning permission could take up to 8 weeks to come through, and might mean we wouldn't be able to take advantage of the existing scaffolding (which will save some costs, and hassle). Also there were rumblings from our builder about our flat roof guarantee being compromised - although the solar firm said they could do the installation without affecting the integrity of the roof. So we have taken the path of least resistance and gone for the smaller west-facing system only. The panels will still generate almost as much as our current electricity consumption.  In comparison to the windows saga, dealing with the PV company has been very easy. They are specifying and fitting everything, much to our relief.