More work on the back roof

With the sudden advent of summer, we’ve been moving rapidly ahead on the rear roof. Three days of solid work has seen

• the roof lights installed
• the two membranes laid
• flashing around 8 of the 10 light frames completed (we ran out of flashing tape and none of the local builders merchants have any more in stock right now)
• the finishing work done to close the gap at the rear gully
• the last leg to support the purlins installed
• the rear land drain laid
• the gravel infill completed

The PET bottle lights are looking and working even better than anticipated. They’ve made an enormous difference to the amount of available light under the roof, even with it being open at both ends. The loose-fitting lids containing the bottles can also be easily lifted off the box frame upstands from the inside on a hot day to increase ventilation.

I’ve spent a good while thinking about how to waterproof this roof. Although not particularly relevant in this context because the space beneath is, and mostly will be, open to the outside, I wanted to experiment with a system that would allow an enclosed space beneath a living roof to breathe while at the same time waterproofing the roof and keeping the structure impervious to plant roots, etc. The next one we do will be over a bath-house where there could be problems with condensation if we don’t think it through well enough.

I chucked ideas around a while with ‘the mens’ – a team of friends and friends of friends who have a knack of turning up to work here with just the right skills at just the right moment. We do this a lot. Practically all the time. I guess some might call it wheel reinventing, but for me, one of the greatest pleasures of pursuing this way of life is to spend time discussing ideas for homemade low tech sustainable solutions to everyday situations in the company of inventive and lively minds with all manner of appropriate experience. And the pleasure in seeing many of those ideas come to fruition in one or another of our quintas is even greater.

This stuff must be hardwired into the human race! It’s basic survival – collective initiatives in solving how to provide food and shelter in the most efficient and effective way possible within a specific context – and there’s a deep satisfaction that’s felt almost at the cellular level from working it out together. Building a home should be like this! A hands-on natural creative process that engages and involves us every step of the way, both personally and communally. Few people have all the skills necessary to do it alone, and even when they do there’s few ideas that aren’t refined and improved by bringing different perspectives to bear on them. This process doesn’t just result in effective shelters, it builds mutually-supportive community at the same time. What’s more, community where the size of your bank balance, ‘professional’ status, race, beliefs, or family background is utterly irrelevant.

But back to the roof … the upshot of this particular idea-chucking session was a roof covering comprising a breathable membrane laid over the wooden planking, followed by Fondaline – a high density polyethylene damp proof studded membrane.

Fondaline is designed for use as a DPM to protect foundation walls whilst allowing easy drainage. Though it’s on a roof here, it’s essentially performing the same function. The air gap between the studs means that any moisture passing through the breathable membrane and condensing on the underside of the Fondaline has an air gap to evaporate into again. Either that, or it runs down onto the breathable membrane, and from there to the drains at the edge of the roof, which it can do easily between the studs of the membrane.

Meanwhile the upper surface of the Fondaline holds water and soil in its pockets, retaining moisture for longer and lessening any likelihood of slippage. It also gives a larger surface area over which the roots of plants can range.

That’s the theory anyway. We’ll soon see how it performs.

The breathable membrane goes down

Cutting openings for the light box frames

Welding membrane edges with a heat gun. The solar system coped with this effortlessly thanks to it being a blazingly sunny day

Rolling out the second run of Fondaline

Cutting box frame openings

Starting to put flashing tape round the box frames

Installed light box. Just the silicone sealant to do now

Boarding complete along the eaves

Land drain laid in the gully

Shovelling gravel down from the track on a makeshift chute

Gully being filled with gravel

The last barrowloads