Under floor insulation and heating

I've got some lovely photos from John showing how he insulated between the joists and then added underfloor heating on top.

For anyone who is considering just insulating between the floor joists, maybe with underfloor heating as well, take a look!

This is just one system - another case study to follow soon will show a slightly different approach.



Electric cables may be higher in the joists than 70mm, so cut the battens at that point. A groove may need to be cut in the underside of the foilboard in some cases.



A little wooden jig (by nail tub) ensures battens are fixed at a uniform depth of 70mm (i.e. 50mm for the board, 15mm for the barrier pipe and 5mm tolerance).



The battens are being cut ready by nailing along joists.



The foilboard has been cut and laid leaving 15mm of the joists above it ready to receive the spreader plates.



The spreader plate sits neatly on the joists ready to receive the barrier pipe. One side will go "away" and the other "back". Though not cheap, the spreaders will ensure a nice even heat and increase efficiency by at least 20% compared with overlay board. This is also useful when thicker flooring is used (say 22mm rather than 18mm).

Eco Houses Under Construction - event 2 summary

On Saturday 30th July, over 35 people attended a very different event – to see a house that 2 weeks ago did not exist! Fortunately the weather was glorious so we could sit in the back garden, looking at the timber structure of the ground floor and first floor levels.

Architect Mike Siebert started by talking about the method used to insulate beneath the house before pouring the slab, using load-bearing insulation to form a “trough” around the perimeter of the house, and beneath the entire footprint of the house (onto which the slab was poured).
The central block-work pillar and the ground floor slab will provide thermal mass to absorb excess heat from the house in hot weather and release the warmth into the house when the temperature falls.

Mike went on to explain his innovative wall construction, the practicalities of working with timber in this way and the u-value of the walls (which will be 0.15W/mK once insulated). There was discussion over methods of achieving air tightness and avoiding cold bridging, particularly around the junction of the outer wall and the first floor – tapes, expanding foam, and insulation between the floor and ceiling will all play their part.


Kris Taylor of EcoFrames Ltd went into more detail about how to get the best value for money with highly insulated timber frames, and also answered questions on another important topic – the source and quality of the timber and distance travelled.

For more about this and other Eco House Group projects, go to www.wbecohouses.co.uk. To see what other projects Transition West Bridgford has to offer, go to www.transitionwb.co.uk.

The Eco Houses Under Construction project is funded by Climate East Midlands, East Midlands Improvement and Efficiency Partnership and Communities and Local Government with a Growing Climate Friendly Communities grant. It is delivered by the charity Groundwork East Midlands.

Eco Houses Under Construction - event 1 summary

Transition West Bridgford’s Eco Houses Under Construction project is off to a flying start, with 2 free events in July attracting over 80 visitors between them. Subsequent events will follow the fortunes of these two building projects (a low-energy refurbishment and a timber frame new build to Code 5) as they progress. The next event is due in late August or early September - to receive details, email info@wbecohouses.co.uk.

On Saturday 16th July, over 45 people braved the rain to attend a talk about one way of turning an ordinary 1950’s brick house into a super-insulated eco house. The speakers were Gil Schalom, a local green architect with longstanding experience in designing ultra-low energy homes, and Alan Budden, architect and expert in the passive house energy model.
Taking a local house that is about to be refurbished as an example, Gil and Alan described the steps that will be needed to bring the heating bill almost to zero. In this example, it is all about super-insulation, air-tightness, and ventilation with heat recovery.
In other words, this refurbishment follows the many of the principles applied in designing state-of-the-art passive houses and the new breed of refurbishments to a standard called “EnerPHit”.