Visited with Infrared camera with aim to check if any thermal issues with party wall. Really cold morning so whole wall cold but evenly cold suggesting construction was consistent and that the assumed construction of the party wall, namely solid brick was correct.
One spot had a clear cold bridge, was wet plaster also, this area will be insulated. The spot is at the top of the wall above the top of the stairs. See photos, one in visible, one in infra-red.
Main purpose of visit was to discuss detailed placing of monitoring equipment. Each monitoring node will have an associated plug socket for the charger. The charger to be charging at all times, the node to be at 1500mm above finished floor, with power cable inside wall trunking. One in back bedroom, one in utility cupboard area, one in living room, one in kitchen and one in roof space. Main PC to be on panel at bottom of stairs also with socket, possibility of fixing touch screen, funds permitting and when all systems commissioned and working.
The relative humidity sensors were discussed and one placed. The aim of these is to see how the breathing construciotn works in practice. The sensor itself to go between the insulation and the wall for the three types of insulation, 1) internal sheepswool on external walls, 2) internal gutex on party walls, 3) external render system on external walls. Stand alone dataloggers with sensors on wires, the datalogger and protruding wires to be wrapped ready for final finishing at end of job.
Some discussion about the jablite floor insulation. This requires fitting to the slab, as the slab is not perfectly level, solution might be to have a 50mm screed but this would require more time and cost so perhaps the fitting the jablite is the cheaper option.
The concrete “pour” for the floor was more of a concrete “transport by wheel barrow”, this was a compromise, between the extra cost required for concrete pump, extra space in residential street to allow this to happen and convenience of 3 hours of people wheeling wheelbarrows full of concrete. The total volume of concrete used was considered greater than volume of hardcore required but this ratio would be a function of the volume of the underfloor void, to my eye i would say the volume of hardcore, concrete and jablite insulation were similar.
A photo of the proclima membrane at the joint with the ground floor internal sheepswool insulation is also shown.
Videos from this visit, include
VIDEO LINK the solar thermal panels from Rotex that were installed this week,
VIDEO LINK a laser level used to check the height of the floor insulation.
VIDEO LINK the plasterboard surface of the 300mm roof insulation on the sloping roof in the back bedroom,
relative humidity sensor placing VIDEO LINK
A colleague, Ian Ridley and I visited the site in the morning. Paul Archer was there. We delivered a box of meters to be installed (gas, water, electric, 2 heat meters). Also we were deciding on monitoring of relative humidity on the cold side of the insulation at several points.
The Gutex boards were mainly completely fitted, using mechanical fixings, something like a giant rawlplug. Lime plaster scratch coat was still soft a few days after plastering. Overall there is a five week schedule from raw wall to insulated and plaster finished wall, compared to a 2 day schedule for drylining type insulation. Comment was, this was long but would be ok for a build of several houses, but for a single one meant delays.
The concrete floor has been poured and set ready for Jablite insulation. Seeing the thickness of this gives a clear feel for how much the volume of this house will be reduced by the insulation.
Cable ducts will be installed within the plaster for monitoring equipment.
One party wall by the stairs will not be insulated and could be a cold wall if there is an unfilled cavity. Infra Red camera could be used to check this next week.
I took two videos, one of the gutex and lime plaster the other of how one piece of the ceiling will be insulated. Click here http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=&release=108727814
Some photos below
Jablite 150mm thick for rear, and 3oomm for front part of house. Thermafleece, 100mm thick
Wood-fibre insulation is being installed to party walls. A lime-hemp plaster is being used to adhere the boards to the walls which have been given a scratch coat and levelled / repaired where needed.
This rear layer of plaster is part of the air-tight layer.
It is important that there are no air gaps between or behind the insulation boards to protect against the formation of condensation in air pockets.
The lime plasters (with no cement) take longer to dry out, which has to be considered in the programme of the works – a total of 5 weeks. So we need to ensure that there is plenty of ventilation in the building whilst the works are going on to aid the drying out process.
The Leca (expanded lightweight clay aggregate) has been delivered to site – this will be used to fill the chimneys after they’ve been swept next week.
Concrete floor was beginning to be poured as I was on site, and once complete, all the structural works will be complete. The roofer is currently on site, and the plumber will be on site next week to work with the roofer to install the supports for the solar thermal panels that face south on the rear roof slope.
Frustratingly, we’ve been told by the manufacturer that the window delivery date has been delayed by 1 week, which is very frustrating – alot of detailing relays on the window installation in terms of air-tightness and external insulation installation. This puts alot of pressure on the final fews weeks of the programme to finish on target.
Air-tight membrane being installed to upper floor ceiling. Being brought down the side of existing partitions, and over the top on new ones.
Sandwood are taking extra-special care in sealing the membrane into the existing wall plaster, and taping every join seamlessly.
An interesting on-site belt and braces approach to the the junction with the front wall that Sandwood have built on site is the double-sealing of the ceiling membrane to the plaster behind the internally insulated external wall, and the wall air-barrier we are installing on the internal side of the sheepswool filled timber battens.
This helps ensure continuity of the air-tight barrier between the party and external walls.
An issue arose with the specified manufacturer’s installation guidelines for the wood-fibre boards to the party walls (these prevent our house heating their neighbours, keeping our heat for our house).
Some wood-fibre board suppliers require you to use a proprietary plaster system (5 times more expensive than gypsum plaster…). We instead sourced a wood-fibre board supplier that would guarantee using normal lime plasters.
To install the boards on the existing plastered walls, a scratch-coat of lime hemp plaster is applied, then a coat of the lime hemp plaster is applied to the entire surface of the wood-fibre boards, to ensure there are no air gaps. This layer bonds the boards to the wall, along with additional plastic fixings. The boards are then finished is a pre-mixed fat lime plaster.
This creates a breathing construction that will help to regulate internal air moisture in the house.
We’ve also decided on site to extend the internal lining to the kitchen walls where the kitchen units are to go, so that we do not need to puncture the internal wall plaster to the externally insulated rear walls, which we are depending on for our air-tightness. We originally only battened out one wall for services. 2 walls still remain solid do provide an element of thermal mass to the room.
Stripping out & demolition works revealing a few unknowns, such as a set in flue for the old copper. we’re removing this chimney breast to give us enough room for MVHR ducts to rise from ground to first floor without making the bath smaller.
Sandwood have stripped of a top band of wall plaster below the top floor ceiling joists so the air-tight ceiling membrane can be plastered flush to the wall, using a Contega fleece tap from Pro-Clima.
A low band of external cement render is being removed from the rear external brickwork so the external insulation can be fitted flush to the wall without any air gaps that could cause condensation. This has revealed some poor quality existing brickwork that needs to be repaired, particularly around window and door openings.
The ground against the rear wall has been excavated ready for the below ground insulation that will help to mitigate the thermal bridge between the external insulation and the internal floor insulation. The psi-value of this junction has been calculated in THERM for an efficiently designed junction that reduces the heat loss through this junction.
Paul is keeping all material order invoices to allow calculations on the embodied energy of all the building materials used in this retrofit., which we’ll be comparing to retrofits using other insulation materials, as well as pulling apart the supply costs.
The internal insulation materials we are using (apart from the EPS solid floor insulation) are all natural materials, will significantly lower embodied energy figures than mineral wool or phenolic foams, as well has having hygroscopic properties to help manage moisture and water vapour within the building fabric and internal air.
Building Control also visited site this week, and had no issues to report, so good progress being made.
Below is a summary of my weekly site visits with the Site Manager, Paul, at Hawthorn Road, so talk through any issues that come up on site during the retrofit, and monitor the progress of the build. As this is a Design and Build contract, Anne Thorne Architects are now appointed by the contractor, but we still liase with the client, MHT, on the project.
The triple-glazed windows from the Green Building Store have a 10-week lead in time, so it was important to check the opening sizes on site asap to confirm the order and hopefully prevent any delays in the window delivery, as crucial to many of the details and air-tightness. A few site dimensions checked and structural steels beams ordered. These are to support de-conversion works, and not specifically related to the retrofit. Timber posts used instead of steel, or beams supported off existing internal partitions to avoid increasing any thermal bridge points with steel columns sitting directly on concrete floor, which is insulated above.
Week 1 – 10 Sep 10
First week on site! Met on site with the site manager from Sandwood, Paul Archer, and the subcontracting renderer, Michel, who will be installing the external render to the rear elevation, and plastering internally, so key to the quality of the air-tightness and integrity of external insulation.
Walked through site and talked through air-tight junctions with Paul, such as sequencing of works and protection of air-barrier during construction. Sandwood have a fantastic record on air-tightness, so really hoping we achieve below 1 air-change-per-hour.
Strip out has commenced, timber ground floor joists have been removed, as well as all existing plasterboard and door and window linings in preparation for this ‘deep’ retrofit.
Onsite decisions included the dropping of a rear bedroom window to avoid clashing with the insulation roof slope; an eaves support detail of the extended eaves over the external insulation.
Sandwood are firstly concentrating on the strip out and structural works (converting the 2 existing flats to 1 family house). Air-tight detailing due to start next week.