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We bought the house in 1983, when our children were 7 and 5. We soon made the obvious energy efficiency improvements of draught proofing and insulating the loft and hot water cylinder. We also fitted an automatic weather compensator for the storage heaters. In 1999 we started a serious drive to cut our carbon emissions and fuel costs by replacing the storage heaters with a condensing boiler and radiators, later insulating the solid walls one room at a time.
We have always been economical and hated waste, so saving money has been a long standing motivation. In addition since the oil crises of 1973-4, we wanted specifically to save energy.
During the 1990’s we became aware of climate change. However it was only in 1999 that we realised just how serious the threat is, especially to poorer countries, and how ineffective were the Government’s warm words on climate change. So our primary motivation now is mitigating climate change.
I (Martin) am a firm believer in doing the most cost effective measures first in order to get the most carbon reduction per £ spent. So (not having cavity walls to insulate) we started by replacing the storage heaters with a gas central heating system which complied with the 2005 Building Regs six years in advance, and this alone cut our heating emissions by 50%.
Then we went on to insulate our solid walls one room at a time using internal insulation, adding secondary double glazing at the same time. In total over the years we have spent about £11,000, and at current prices we are saving £1,200 a year on fuel bills. Between 1999 and 2013 our fuel cost savings at historic costs already cover our entire capital outlay, so the cost of cutting our carbon emissions by 70% is nil and going negative.
Saving energy (in a cost effective way) is the essential first step towards the necessary zero carbon economy. We are pleased to report that our grown up children are doing the same, with energy saving grants and loans from the Bank of Mum and Dad.
This Victorian semi-detached house was built in 1903 with 4 bedrooms (plus a further two in the attic). We liked the Victorian character of the house as well as its location, but the deciding factor was its size – we wanted 4 bedrooms. When we moved in, the kitchen and bathroom facilities were minimal, there was no draught proofing nor even loft insulation, leaking gutters and rising damp. The hallway was very gloomy so we left its light on most of the time.
The key changes were condensing boiler, draught proofing, solid wall insulation and double glazing. Other energy saving measures included A rated appliances and low energy light bulbs.
We have stopped buying ordinary CFL low energy light bulbs, in favour of LED lights with the traditional bayonet fitting. The LED’s seem expensive, but last much longer, so work out cheaper per hour even before considering the modest saving in electricity use. The hall light which was once a 40W incandescent, then a 3W CFL, is now a 1.7W LED which claims to last 25,000 hours.
• Condensing combi boiler with programmable thermostat and TRVs on radiators. All underfloor pipework is insulated, and six years later we discovered that we had complied with the 2005 Building Regulations
• Double glazing: Some UPVC replacement windows where the old windows were rotten at the south facing rear
• Built a door to stop heat rising up the attic stairs, and draught proofed doors and windows, using ‘Stormguard’ V-seal, particularly on doors which are twisted so do not shut snugly into their frames
• DIY external wall insulation: The two outside downstairs rooms are sheltered by a tandem lean-to brick garage. We exploited this by applying cheap DIY external wall insulation which is inside the garage so needs no further protection from the weather. We used 200mm of fibreglass loft type insulation hung from the wall, then studs at intervals of 78 inches to support old doors (£10 for 20) used on their sides as cladding. The cladding presses the insulation gently against the wall and also protects garage users from itchy insulation while providing a solid surface
• Internal wall insulation installed in walls in ground floor rooms plus bathroom, using 60 to 100mm of foil-clad polyurethane foam (Kingspan or Celotex) positioned on the wall and secured by battens on the inside (the warm side). Installing the insulation separately before the plasterboard allowed us to use expanding foam to seal around the edges giving a much better vapour barrier than the common system of insulated plasterboard. Placing the battens on the warm side eliminates risk of rot, and allowed us to put a further 25mm of polyurethane foam between the battens before finishing with plasterboard screwed to the battens. We used 25mm battens to match the available 25mm insulation. The first rooms were done by Martin, later ones by a local builder who we knew well, under close supervision to ensure a proper vapour barrier
• Loft insulation increased from 100mm to 200mm. We laid extra joists (reclaimed ones) across the original ones and insulated between them, then boarded over, so we have a boarded loft despite the extra thick insulation
• The fridge freezer is rated ‘A +’ and the oven and washing machine ‘A’
• All lighting is by low energy bulbs, including some SMD LED candle bulbs, available on line
• Mostly secondary glazing using permanently fixed glass, with ventilation by separate vents
• Hot Water: In the kitchen to avoid a long pipe run (or later a long wait for a combi boiler to warm up) hot water is heated by electricity in a 10 litre mains pressure tank made by Steibel Eltron. This is much more convenient, and although electricity is expensive and carbon intensive this is offset by the high pipe losses saved for water uses which are small and frequent (in the same way that dishwashers and modern washing machines use electricity to heat the water). Conversely the shower, which has a small number of quite large uses, is fed by the Combi boiler
• Renewable energy: The house faces a little West of South at the back, which is an excellent start for passive solar gain, BUT, like many Victorian houses it has a rear wing extending beyond the rear main reception rooms. The rear wing is two storey so it obstructs the sun in the downstairs rear main rooms, in the west room in the morning and in the east one in the afternoon. To get round this I (Martin) googled “solar warm air collector” and got some design ideas as I found that these are common in the USA, most of which has vastly more winter sun than we do. So I built one which takes air from the downstairs room to be warmed in a collector on the unobstructed wall of the bedroom above and drawn back by a fan into the downstairs room at between 35 and 60 degrees when the sun is shining between 10 a.m. and 4 p.m. That sounds hot but remember that the heat content of a litre of air is very small. The end result is a modest extra solar gain, but the timing is still poor, since when you most need heat is early morning and evenings. So if doing it again I would use a water based system, collecting the heat in a thermal store for use in the evening or even on the following morning. However if you want to make a warm air collector google “solar hot air collector” which will show mostly US information. Then under advanced search select UK as the region for UK information. Also see here. Remember that in the UK your home will have to be extremely well insulated and airtight to rely on solar heat only or even mainly. You can also email Martin for technical details, see ‘contact’ tab .
Our refurbishments have cut heating and hot water emissions by 80% and electricity emissions by 55%. The money saving is more than I ever thought it would be; every time gas prices go up I feel smug.
After wall insulation we no longer get cold air flowing off the walls along the floor and it’s more comfortable in the winter. The well insulated rooms cool down much more slowly, so the heating normally goes off during breakfast, and often is not needed again until 5 p.m. even though we are in a lot during the day. We turn it off for the night an hour or two before bed.
The history of the light in the hallway charts the march of progress in lighting efficiency: in the 80s it was a 40watt incandescent (normal old fashioned bulb), by 1990 a 13watt early bulky CFL low energy bulb, then a modern 5watt CFL low energy bulb, and now it is a 3watt SMD LED, which is slightly brighter than the old 40watt dinosaur.
Solid wall insulation has a much longer payback than replacing an ancient boiler or storage heaters. However it lasts almost for ever, so long after the new boiler has been replaced, the insulation will still be doing its job, requiring no maintenance and with no instructions to lose or get wrong. So the solid wall insulation is, in the long run, the more cost effective. If the World runs out of gas, the boiler won’t be any good but the insulation will still be working.
Period details: Picture rails, window architrave and skirting were removed carefully and put back afterwards, battens having been positioned with this in mind. Period coving has to be replaced; a shop selling imitation antique coving put us in touch with a man who came and made a template of our coving, then came back a week later and EXPERTLY glued up a set of 1m lengths of new made to match coving smoothing all joints until invisible. Not cheap but worth it.
Yes. Where I expected fittings such as radiators, curtain rails and, especially, high level kitchen units, I made the battens wider. This gives you a bit of leeway in the fixing position and you are less likely to split a batten. In order to run services I omitted parts of the 2nd insulation layer, between the battens. Battens can run vertical or horizontal (or a mix).
25mm battens are ample as there are rigid foam boards behind them; 19 mm would be quite strong enough but I put extra insulation between battens and 25mm is usually the thinnest insulation available. I can omit this extra insulation where I need to run services. I use 4 fixings per 2.8m length, or more if hanging kitchen cupboards, radiators etc. there, when I also use a wider (not thicker) batten to allow a margin for error in positioning the cupboards etc.
Yes, with long screws into rawlplugs through the batten, the Celotex and into the external wall. This penetrates the VCL, but the batten covers the hole, and the screw head is snug in the hole. To be extra sure about the VCL you could mastic the screw head into the hole, OR cover it with aluminium tape.
And yes each screw is a small cold bridge; I guess it could be improved a bit by using the plastic hammer-in plugs which are often used in external wall insulation.
I guess if you wanted to really go to town you could put 25mm of Celotex over the battens, secured initially with a few dabs of mastic; then when you put the plasterboard on, its screws would go through the 25mm into the battens but not into the main insulation. That way neither the main screws with rawlplugs nor the plasterboard screws penetrate the full insulation thickness.
I used 25mm battens then thickish insulation behind. My standard spec, using Kingspan or Celotex, is 50mm wall-side layer then battens, with 25mm insulation between them, giving a U value in the region of 0.2. Using polystyrene or eco materials you would need 100mm then 25mm to get the same result.
Where it is necessary to restrict thickness of insulation (e.g. in window reveals) , a little insulation (especially if it is Kingspan etc) is a lot better than none, so you could put battens straight onto wall with 25mm proper insulation only between them, or maybe 19mm battens with 6mm insulation behind (if you can source it) and 25mm insulation between. Insulating behind the battens also protects them from cold and hence from condensation, and from any penetrating damp. The reveals which I have insulated are quite small so I just glued insulated plasterboard, with 20 or 25mm insulation, into them.
I think the insulated stud way will become the standard where people use soft insulation between the battens. John Doggart (another Superhomer) has used it in his SuperHome, and was able to buy studs with the insulation already attached, though probably cheaper to DIY it.
You have identified a drawback of the ready insulated plasterboard, as that plaster will not stick to aluminium tape, so on the one occasion when I used the ready insulated plasterboard, I relied on the skim plaster and crossed my fingers. I foamed between the floor and the bottom edge, which is covered by the skirting and the bottom inch not plastered, and then plastered the joints at the top and sides and relied on the skim plaster to give a hopefully adequate seal including joints between plasterboard sheets. Clearly not such a good seal as “my” warm batten system.
Another SuperHomer used ready insulated plasterboard, but noted that the boards came with the plasterboard slightly overhanging the insulation, giving a cold bridge where it was impossible to butt the insulation tightly together. So he carefully cut the plasterboard back enough to reverse the overhang so he could butt the insulation together properly, and then he filled the gap between plasterboards before skimming. Depending on the filler used this could also give a reasonable vapour barrier.
However having used both systems, I find that the warm batten system takes no more labour, gives a better result, and saves money on materials. At first sight you would expect the insulated plasterboard system to be quicker, but it is difficult to line up the boards accurately, and my builder who has done both systems for me agreed, to his surprise, that the insulated plasterboard system was no quicker.
One advantage of my system is that the whole insulation system is anchored into the brick wall, avoiding possible problems with poor adhesion to the insulated plasterboard and poor adhesion of old plaster to the wall (so I don’t bother to hack off old plaster).
The sheet(s) on the first wall you do go right up to the next wall. Then when you start on the next wall butt the sheet end against the face of the sheet on the first wall, but leave a 15mm gap to get the foam gun nozzle in to seal the joint.
I use just the standard no–nonsense foam, though I use a proper foam gun – £17.99 well spent. It takes foam cartridges with a different head, but otherwise the same and much the same price. But you will halve foam waste and halve the labour to apply it.
Between insulation boards I have used foam into a 15mm gap, filled to full depth, but now I just butt the boards and apply aluminium tape.
Against walls, floor and ceiling I fill the gap to the full depth to maximise both vapour barrier (the foam is not 100% vapour resistant) and insulation. The main vapour barrier is the room side surface of the insulation, which has aluminium foil covering, plus the sealing of gaps.
Where you have a window reveal there is usually only space for a very thin layer of insulation, but fit what you can to avoid condensation on the cold bridge which will otherwise result. I use the dreaded insulated plasterboard, and for such small pieces I just rely on plasterboard adhesive to attach them. To get complete plasterboard cover over the insulation, the plasterboard on one face (the reveal or the wall) needs to project beyond the insulation by the thickness of the insulation on the other face, so you need to cut away the insulation from the projecting part of the insulated plasterboard used on the reveal (or stop the wall insulation 20mm short if using 20mm insulation in the reveal).
In the reveal you could instead use 25 or 20mm of insulation and separate plasterboard, relying on adhesive for each layer (for glue adhesion, first sand both sides of the foil which covers the insulation). You can put rawlplugs into the reveal through the plasterboard and insulation, but if you have dud holes where you hit mortar you can end up with a Swiss cheese effect. When using battens any Swiss cheese effect is in the battens where it can be sealed with aluminium tape and then hidden by the plasterboard.
If there is no insulation on the reveals you will get condensation there, so line with the plastic sold for fascia as mould will not grow on it. It can be glued in place and the lip wraps round onto the main plasterboard for an inch or so, or you could cut off the lip and butt it onto the plasterboard on the wall. You could also use it instead of plasterboard even with insulation.
If you keep the old Victorian outer frames there is no reveal because the frames, behind the architrave, are flush with the plaster on the wall. In this case use wood or MDF to build the inner inch or so of the frame out to the thickness of the wall insulation plus plasterboard, then butt the insulation and plasterboard up to it. Seal the butt joint with foam and it will be hidden when you put the architrave back.
Yes. Two ways to do this:
1. On Victorian windows remove sill and any architrave (it is usually just nailed to the window outer frame, and can be prised off with care), fit a filler piece of wood, then reattach original sill and architrave. Or you could make up a single piece, but perhaps harder to replicate the original detailing.
2. Or, especially for deeper sills, extend the insulation and plasterboard up till flush with the surface of the window sill, then cover the old sill and insulation and plasterboard with fascia plastic.
Unless I were to have space to use my proper system, I use the insulated plasterboard with a mere 25mm of insulation just glued to the reveal; seems to work well for such small areas. If no space to use expanding foam just seal with mastic. 25mm of insulation sounds pathetic, but it is enough to stop condensation, so worth doing.
The plasterboard has negligible insulation value compared to the actual insulation, so there shouldn’t be any condensation on the warm side of the actual insulation, and vapour which gets through it stays as vapour so can come out by the same route as it came in. Official advice for when using more than one layer of insulation is to put the thicker layer against the wall, then the thinner layer, so that any vapour which gets through (gaps in) the vapour barrier meets the join between the two layers at less than half the temperature drop.
Any good vapour barrier, such as DPM plastic sheet, will do fine, as long there are no gaps, which means securing the edges to walls floor and ceiling, usually with 25mm square battens, and overlapping joints between sheets with a fold and tape.
In addition you need to consider possible water damage to the unprotected Kingspan on its cold side from any water coming in through the brickwork, so, at least on the South and West walls, either protect with a breather membrane or create a small air gap. One way of making an air gap is to put non rotting battens, say 20-25mm thick, behind the insulation. These could be plastic or extruded polystyrene (which unlike expanded polystyrene and Kingspan is fully water resistant). Put them directly behind where the wooden battens will go, mark the position on wall/floor/ceiling, and give minimal securings; then the screws for the wooden battens will hold the plastic ones in place, and there will be no risk of bowing the insulation with the wooden battens.
SDS drills are great, easy quick and effective. They go through hard brick including “black hearted” bricks at 5 times the speed of old fashioned masonry drills, and their chucks last MUCH longer. The drill bits are expensive but, because of the superior action of the drill, the bits last MUCH longer, so cheaper in the long run. I have a “pneumatic” one, a German make. I also made the mistake of buying a cheap and powerful Chinese one, not pneumatic, it is so powerful and violent that it cracks the brick instead of making a hole!
I didn’t consider it, as wood is easier to use, and being on the warm side no risk of rot. On the other hand if you need to screw into the studs later, when you have forgotten where they are, it would be much easier to locate metal studding using a magnet. My preference would be to make the wood magnet-responsive to be easy to locate; you MIGHT be able to do this by painting it with a paint containing iron, google iron oxide paint.
An advantage of wood is that it pretty much seals the screw holes in the insulation, which steel studs would not do as they are hollow and full of holes.
On one wall there was a possible damp problem, so I used a different system with a framework on the cold side (also often necessary if a wall is very uneven), and there I used metal studding to avoid risk of rot; It was more difficult than wood cos of my being new to the system, but with experience it would be quite easy. Then I put the insulation against the frame (NOT between the steel studs as that leaves a cold bridge and probably gaps where insulation meets steel stud) , sealed it, and screwed plasterboard through the insulation into the frame [slight damage to vapour barrier] having marked the stud positions on the floor and ceiling.
To combat vapour leakage, nothing except that the wood battens seal the hole fairly well. You could put a bit of Aluminium tape over the screw heads I guess. Re: cold bridge, I lived with it; if someone makes strong enough plastic screws that would help, but they would have to be strong enough to bite into the plastic rawlplugs. With steel studding I guess only steel screws will bite into it.
One thing I have learnt is that with my system the plasterboard stays in position with no cracks appearing, while with the insulated plasterboard and adhesive system you usually get slight movement causing fine cracks at joints between boards (as well as an uncertain vapour barrier).
When we had 3 quotes from plasterers to insulate a room two years ago, two of the plasterers preferred to use insulated plasterboard on battens, at no extra cost, to avoid cracking. They were going to put the battens against the wall (on the cold side) but were happy to use instead my system with separate insulation and plasterboard and warm battens between them, which was what we did. They wanted to leave a gap at the bottom, which all plasterers do it seems, to avoid the risk of the plasterboard getting wet, but agreed that the insulation could be right to the floor as it is less sensitive to wet. So I asked the one who we appointed to leave a 15mm gap at the bottom of the insulation (which he did though it was only about 8mm in places) and then I sealed it with expanding foam. And the same around the other edges.
For ducting we use ordinary 68mm drainpipe, but you would have more heat and might need something wider, maybe 100mm soil pipe. Or you could use metal chimney liner (mix of flexible and rigid perhaps) or proper air handling ducts (often square). When our collector gets very hot it gets a nasty plastic smell, while the proper air ducts are usually metal I think. In your stove heat system the duct would not get so hot, unless it was very close to the stove, so plastic is probably OK, though metal would be better.
We have 2 pipes, return to the solar collector and flow from it to the room. We pump the flow air with a nice big in-line centrifugal fan on a lowish setting; using a big fan on a low setting is quiet and energy efficient, ours uses 18 watts on speed 2, 11 watts on speed 1. The fan is at the end of the flow pipe so it is sucking, more efficient than pushing. The return pipe is passive. The fan is a Nuaire flatmaster anti-condensation unit which I had kicking around, see here; you want item 9, last on page, £246.24. Or you could use something cheaper but this one has a filter and is quiet and energy efficient.
Our original plan was to run the ducts under the wooden suspended floors, hanging into the crawl space from the joists. However so far the air just comes from and to the south facing Living room (and up and down to the solar collector via ducts attached to the outside of the wall and insulated), so no horizontal air movement needed.
My system is controlled by a cooling thermostat, aka a reverse acting thermostat, which is set to its highest setting of 30 degrees C, so when the air in the collector reaches 30 the fan switches on.
I just cut off the surplus with a sharp knife. It still looks messy but will be hidden by skirting board.
Foaming vertical joints is same, mess is hidden behind plasterboard .
Foaming overhead joints is “interesting!” as gravity is against you. One way is to stuff bits of solid foam into the gap, then just fill remaining gaps with plaster or filler or decorators caulk in a gun. Alternatively I had fair success covering joint with wide clear tape, then cutting slits big enough for nozzle every 18inches or so and foaming into the gap – the clear tape lets you see the progress of the foam. Next day remove tape and trim away bulges. Remaining mess is covered by plasterboard and/or plaster. You could use this on vertical joints too, to reduce mess a bit.
Spend £10 or so in Screwfix for a metal foam gun. Reusable any number of times, you buy foam cartridges with a different top. Saves time as much easier to use, and money as you can leave a part-used can on it for weeks. Just scrape dried foam off tip before next use. You have to leave a can on it, OR if it will not be used for a month or more buy the gun cleaner can and clean it out.
Yes I did. This is commonly used where the wall is very uneven or incurably damp. My system is quicker to install and takes up less space and the only wood is the battens which are warm and dry being on the warm side of the insulation, so I used it on most of my walls which are true-ish, being a Victorian house. However I did use the frame system in some rooms, ventilating the space behind to avoid rot in the frame. You only need a small amount of ventilation, and it should resist the entry of rodents and insects.
On a cottage with uneven walls, or if you want to go straight across a wall with an unused fireplace, you would use the frame system, with a DPC (a piece of builders plastic) and some insulation between the sole plate and a solid floor.
The (ventilated) air gap behind the frame is cold, so should be insulated and air sealed from rooms beside or above or below if they are not insulated the same way with the frames aligned.
Screws are a weak point in either system. To limit vapour transmission around the screws I put a bit of self adhesive aluminium tape over the heads of the long screws going through the battens and insulation and into the wall. For heat conduction perhaps I could have used plastic screws? Screwing the plasterboard to the battens is not a problem as the battens are within the heated envelope, whereas with a frame the frame is usually cold. In theory you could put the insulation behind it but it would be very fiddly, since the reason for using a full frame is to have an air gap behind it.
In the solid floored kitchen we were able to cut the floor tiles at the edge and dig a narrow trench down as far as I could reach, about 60 cm, and insulate it, joining the insulation to the main wall insulation with expanding foam (easier than trying to carry a single sheet down into the trench). This was to limit heat loss through the floor, as most of any floor heat loss is at the edges. This avoided ripping up nice Victorian tiles and was much easier as we were lucky in that under the tiles we just had to dig out an ash base, not battle with brick rubble. It would be hard to do this with a frame system as we removed the bit of floor which the frame would stand on.