This Winter, Insulate The Roof Before Getting Solar

As winter closes in again I’ve set about some improvements to casa del cottage.

So can you retrofit efficiency? Yes, but it’s difficult to get the best results – especially when you’ve already got solar. As a qualified builder I often lament my fellow licensees are sometimes hopeless. Many just don’t know how important it is to get the details right and maybe more of them don’t care?

When you add a tendency to be conservative or even suspicious about changes in building practice, and undergird the whole system with cheapness, the long term results are uncomfortable and expensive.

Getting What You Pay For

To some extent people get what they deserve. Keeping up with the Joneses means flashy finishes and pretty porticos eat up the budget when we should be spending big on insulated slabs and extra thick wall framing.

Sadly we all pay through the nose for fashion. Despite some improvements in standards, the woeful design and execution of Australia’s glorified tents is generally overcome by brute force and energy consumption.

Investors buy them, builders throw them up and energy companies collect revenue, but it’s the residents who pay and pay, for the poor decisions, season after season. Renters are most vulnerable because they have no power to improve the situation.

Insulation Matters More At The Outset

My little house probably dates to the 1940s. It has weatherboard cladding, fibrous plaster lining and precious little else in the walls. Even though there’s mineral fibre/rockwool insulation on top of the ceiling, the floor is uninsulated and there’s gaps and drafts everywhere else.

Recently, we had a renovation done on the bathroom, which was built under the original verandah outside the house proper.

The whole project was a bit of a disaster (it makes me wish there was a “bathroom” option for SolarQuotes but that’s a story for another time).

In green we see the electrician has simply discarded the ceiling insulation, while the carpenter forgot about the niche and left a piece of wall insulation to fall out.

Retrofitting Is A Pain

While the bathroom walls were stripped bare, the builder stuck batts into all of the wall frame and I made sure they fitted properly. Except where they fell out because the carpenter wasn’t competent and didn’t give a rats arse.

What is now an internal wall of the house has insulation, but it only extends to the lower ceiling height of the bathroom. The top section of wall remained uninsulated like the rest of the external walls.

I took a thermal image during summer, which shows the problem vividly.

Having A Crack

I curse myself for not realising at the time, but insulating the wall would have been far easier when the bathroom ceiling was out.

However there was a spare bag of insulation left over and I thought I’d have a go at installing some – only problem was the very poor access. Any normal person would pull some roofing iron off to get into the limited space, but my options were limited by the zealot who’d already put PV solar panels everywhere.

This is a good example of why we recommend sorting out roof improvements or repairs before installing solar.

I have opened an access panel under the verandah, so the bathroom exhaust fan could be ducted outside the roof space, hence I threw a long cupboard door in there to crawl on and pushed a few batts of rockwool in front of me.

Insulation wrapped around the corner & held with string. Legally none of this wiring has to be clipped, none of it is “accessible” unless you’re a madman.

What A Bloody Mission

Using a bread knife to cut insulation to size, an impact driver to put a few screws in and then builders’ string line to keep the batts in place, I worked along, feeding the pink fluff as far as I could into the cavities.

It was hot, dirty and especially awkward because I didn’t want to crash through the new bathroom ceiling, but nor was there enough space to crawl. The distance from my knee to my backside was more than the available headroom.

A Mildly Unsatisfying Result

No matter how valiant the attempt, the problem was always going to be how well the batts could be fitted, and in this case it was hard.

Insulation works when it sits against a surface. It has to trap air and prevent drafts carrying heat away, but it mustn’t be compressed.

Perhaps the best way to demonstrate is when you get into bed, you instinctively pull the bedding to your neck don’t you? Pressed against your skin, an electric underlay might be hot, but the air around you under the blanket takes a little while to warm.

Stark reality hits when you lift your knees. Skin remains warm where the blanket stays in contact, but cool air from the room rushes in to fill the void.

Poorly fitted insulation suffers the same. If your “blanket” has gaps totalling 5% coverage, you’ll lose half the rated performance.

An enclosed verandah forms the bathroom, hence the ceiling is lower outside. Hallway was not insulated but is “inside” the house now. Roof space is blazing hot.

The wall above the ceiling line is now better insulated but nothing to write home about.

Do It Right The First Time

In many cases poor buildings are impossible to fix. You can’t turn the place to point at the sun or get under the concrete slab to insulate, but that doesn’t mean we shouldn’t make improvements.

Double glazed windows might be an option, I’ve done them on the cheap myself. Walls can be improved if you gut the house, or cut a few dozen holes to pour beads into the cavity, but it’s difficult to increase wall thickness.

Draft stopping and ceiling insulation is a simple and very effective improvement though. It is rewarding impact for the effort spent.

Whatever efficiency you can claim will help with bills and more importantly, make your place inherently more comfortable to live in, even before you turn on the climate control. That reduced energy consumption means that when you do get around to installing solar panels, a smaller and cheaper system may suffice.