The Haringey PassivTerrace

winner of Retrofit for the Future

Work progress – 3 BC visit 4th October

with 2 comments

Notes from project meeting and subsequent site visit on 4th October. Ben Croxford

Work progressing very quickly, most of the air tight membrane work between first floor and loft has been finished. Membrane of the tyvek type, plastered into wall about 200mm below height of ceiling.

Lintel of back window lowered to help achieve this. Met Charlie on site and discussed several issues. Potential for monitoring humidity levels within the internal wall insulation construction for the front exposed wall. Thoughts about this were that the largest span of wall available for monitoring was on the incoming corner by the bay window, would need 2 RH% sensors one on the external side of the thermafleece, one on the internal side, progress of build too rapid to get Zhuhui to make up calibrated sensors so could use HOBO with extended sensors, will check tomorrow if possible.

Change from Pavodentro to Gutex, fibreboard due to Pavodentro requiring particular type of lime plaster to finish, Gutex less fussy about type of lime plaster. Humidity problems on this surface far less likely so monitoring not so interesting for my colleagues at UCL. However if we can get sensors in time we will try to monitor this also.

Metering: electricity meter likely to be moved to understairs from current above door position, I hope we can get extra gas meter and heat meters installed into boiler cupboard.

Floor void filled with hard core, some recycled bricks from works, a skip load has very low cost, leaving 150mm for concrete pour due today, Wednesday. Jablite floor insulation to be laid on top of concrete, so making the house “lightweight” in terms of thermal performance. Very hot nights could lead to overheating in future warmer climate, as no way to store coolth. Heater battery for WHMV system might be possible to convert to a “cooler” battery if source of coolth available. Idea for future projects might be to use concrete floor under the insulation as this source of cool.

Discussed air tightness difficulties with Charlie, chief problems, are expected around penetrations of waste pipes, all will be extended on the outside to make it past the extensive external insulation, joins are a weak point.

Discussed first floor joists into wall, as external insulation on all rear walls the joists are “warm” so no condensation problems should occur. Joists into front wall could extend beyond warm envelope into front exposed wall?

Final discussion was with Paul, more general around future ways to best insulate floors of Victorian type terrace houses. His suggestion was take up floor boards, lay down membrane, then insulate, then floorboards, this would keep the floor joists in the cool ventilated floor vent perhaps avoiding condensation.

I took some small videos of certain construction details to be posted later.


Written by Ben Croxford

October 6, 2010 at 8:00 am

Posted in Uncategorized

2 Responses

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  1. Interesting point about concrete floor and thermal mass.
    We originally wanted to retain the existing timber joist floor, but for cost issues, went to a concrete slab, so maybe missed a trick to use this opportunity to maximise thermal mass.

    Putting the insulation on top of insulation requires no screed, so do not need to excavate to a deeper level, and ATAP used this build up previously, but we should review in light of summer overheating.
    In this house, the living room has windows front and back, so opportunity for cross ventilation in summer, and living room north facing.


    October 8, 2010 at 2:55 pm

    • Perhaps something we can look at in more detail during next summer!


      October 11, 2010 at 10:18 am

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