So good to see you James!

I’ve just had coffee with one of the people who helped us most during our retrofit. James King, Founder of Unity Lime, a supplier of everything wood fibre and lime, was so generous with his knowledge when we needed it most.

If you’ve read any of my blogs you’ll know we came late to the game of retrofitting. Setting out to build an extension, we realised part way through that the whole house needed work to make it environmentally friendly and to save us money. So we began the task with plenty of determination, but minimal knowledge – and that’s where James was so helpful.

Wood fibre insulation

Our architect did an eco design for the extension so we had a starting point. The insulation he recommended was Pavaflex, wood fibre batts that are robust, easy to use, have a low U value, are low carbon and compostable at the end of life – all supplied by Unity Lime. We understood this process, as did our builder, so we just continued in the same way. As we hit snags, James was on the end of the line to help and made every effort to get the materials to us as soon as we needed them. And given this was in the early stages of the covid lockdowns, that was no mean feat.

Open House

The house has been finished for two years now, so we’ve had two comfortable winters with much lower energy bills. I’ve got the book written and it’s out there in the world doing its job of encouraging others to think environment and energy efficiency when working on their homes.  As so many people ask how we did it, I decided to offer an Open House this year for Sustfest run by the Sustainable St Albans. Then people can see the end result and discuss how we did it.

But going to see a well-insulated home is pretty boring – there’s nothing much to look at. You can feel an energy efficient house and you can see the ventilation and air source heat pump, but the insulation is definitely not on view.

I decided I’ll blow up photo’s and put them in situ to show what lies underneath the lime plaster. Then John came up with the brilliant idea of making a model of the joists so I can show directly how we insulated under the floor.

Breathable membrane

And that’s where James comes back onto the scene. Putting wood fibre between the joists of a suspended floor requires some form of support system. We used a breathable membrane, slung over the joists, and fixed at a depth that allows air from the air bricks to still flow freely underneath. The wood fibre batts were cut to size – every gap was different – and slotted into place, sitting just proud of the joists in order to form a tight seal once the floorboards went back down.

What has this to do with James? Well we still have some Pavaflex sitting in the shed, but the breathable membrane was all gone. And we’d been so pleased at having exactly the right amount too! But now we needed just a small amount. I called up Unity Lime to ask if they had a spare bit lying around that we could buy and I got a call back to say that James was in our area and would drop some over to us free of charge.

So I put on the coffee machine….

And we talked retrofitting and insulation for a couple of hours. How my life has changed! It used to be all leadership development and strategy meetings, now I can’t think of anything more interesting than airtightness and lime plaster. I know, I know – you’ll think I should get a life – but first let me tell you about the benefits of pavaflex over PIR………………….


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