Nice wooden floor - shame about the draughts...
Turning our Victorian terrace into an ecohome: part three - floors
1st July, 2010
Insulating the floor can be fiddly, messy and costly. Luckily, there are simple, cheap options too as Sue discovers
Well, this is all taking rather longer than I expected. The main problem is that I seem to have become an ecorefurb research junkie – and the more I know, the less sure I am what the hell to do.
The other weekend I visited several houses in north London that were part of an ecohome open house weekend. Some of them had gone the whole hog – wall insulation, solar thermal and PV panels, rainwater harvesting connected to the toilets and washing machine and passive solar conservatories. It was incredibly inspiring. The houses ranged from the type you’d see in a glossy interior design magazine to the more home-spun version of eco-living.
There’s no right or wrong obviously, and it was great to see how people have made their Victorian homes more energy efficient in different ways and with different budgets. The open weekend was organised by Victeri – the Victorian Terrace Energy Reduction Initiative but if you’re not in London you can find ecohomes near you through the Sustainable Energy Academy’s Superhome scheme.
One thing I wanted to find out about was floor insulation. I’ve been in a quandary about how to deal with our cold, draughty lounge and hall floorboards and was hoping to be enlightened. One thing I realised as I enviously toured around the houses was that having a cellar makes insulating your floors a breeze.
At one house, we went down into the cellar to view the insulation boards stuck snugly between the joists. The rigid polyurethane foam board such as Kingspan or Celotex can be easily cut to the right width for whatever space you are insulating. If you can stand or even just kneel up in the cellar you can easily stick the boards under the floor, cut to size and dropped in between the joists, to rest on supporting nails or battens.
Apparently around 10 per cent of the house’s heat is lost through the floors so you’ve made an instant, easy and relatively cheap ecorefurb win. This house had also gone into ecorefurb goldstar territory by putting down salvaged wooden floors on top of their floorboards for even more insulation – the stunning kitchen floor’s claim to fame being that it used to be Crystal Palace basketball court.
Option one: the whole hog
But back at our house unfortunately we don’t have a cellar, so if we want to insulate our floors we will have to do it from above – that involves taking the skirting boards off, lifting the floorboards, putting fruit netting over the joists and using the netting as a sort of hammock to hold loft insulation roll as close to the underside of the floorboards as possible.
I went onto the Green Building Forum and found some useful practical advice too, such as using the type of loft roll that is enclosed in a long plastic/foil wrap. As the person posting the advice says, ‘This reduces the amount of fibres falling about everywhere and if you have a staple gun, you can staple it to the sides of the joist until you can get your netting or whatever to hold it up.’
Having an airtight system is key, it seems, so the insulation should meet the walls (unlike in the loft where you need to leave a gap at the eaves for ventilation). The person on the forum also suggested ‘using thin plywood or similar to hold the insulation in place rather than netting, maybe even plasterboard for its fire resistant properties. This makes for an easier and tidier job as long as you can get the big sheets down there.’
This sort of practical advice is invaluable – but I still have more questions. How do you connect the netting to the wall? What with? Would it be secure enough to hold the loft roll indefinitely (I really wouldn’t want to do that all again if it fell down and anyway, how would we know?) Could it get damp? Could animals decide to come and live in it? What if it sagged and blocked the under floor ventilation holes? Would we have to move all the furniture out to do it or could we just shift the furniture around the room? Do we have to do it before the walls are insulated or could we do it at a later date? And so on… hence my paralysis.
I’ve had several builders round and the general reaction is, 'Well we can but….'. It seems it’s very fiddly, messy and is costly in time. You can do it yourself if you’re handy, and if you can keep small members of the family away. So I’m still undecided whether to go the full ecorefurb hog and insulate the floors, given all the disturbance.
I’m also worried that some floorboards would inevitably get broken and then I’d be left with the job of getting floorboards to match, which would mean re-sanding and re-oiling the whole of the floor.
Option two: draught-proofing
A half-way house is just to draught-proof the floors – by blocking up any holes or gaps between the skirting and the floor boards and around radiator pipes, etc. This can be done with decorator’s caulk (slightly easier to use than silicone sealant apparently) and a mastik gun. If the hole is big, fill in gaps with thin strips or balls of newspaper and then use the caulk so it doesn’t fall down.
A friend has done it recently and assures me it was even ‘therapeutic’. So I’m leaning towards that option. Of course putting well-fitting carpets or laminate down with a thermal underlay underneath is the simplest explanation, but we like our floor.
You can also block up the gaps between the floorboards and a top tip from a friend is to get a load of sawdust from a timber merchant (or from the dust when you sand the floor – if you do), mix it with PVA glue and add some brown paint, then put it between the gaps, leave it to dry and sand it smooth. Sounds cheap, relatively easy and non-toxic which is good as I have tried it before with a product from the hardware store but the fumes were unbearable.
The thing about just filling the gaps is that it stops the draughts but it doesn’t insulate – it’s like buttoning up your cardigan on a winter’s day – it helps keep the wind out, but what you actually need is a thick coat to keep warm.
And the winner is...
I have had one small success during my research though – the double-sided draught excluder. This is two sausage-style draught excluders connected by a flat piece of material or plastic that goes under the door. So the draught excluder moves with the door thus getting over the problem of it being knocked away whenever someone leaves the room. You can even get versions suitable for outside doors. There is a whole variety here: starting at £2.49 – which is probably the cheapest and simplest energy efficiency product I’ve come across yet.
It may be summer but I’m going to buy one anyway just to make me feel like I’ve done something.
Sue Wheat is a freelance journalist
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