Part 4 - Preparing and installing domestic retrofit system 2

Question 1

what is a warm flat roof?

Answer 1

A warm flat roof, or a built-up roof (BUR), is one where all the insulation (1) is above the joists/deck (2), making them part of the warm fabric of the building. The insulation is immediately below the waterproofing layer (3). The vapour control layer (4) is above the decking but below the insulation. The insulation can be adhered, mechanically fixed or loose laid.

Question 2

what is a cold roof insulation?

Answer 2

A cold flat roof is one where the insulation (1) is between, or between and below, the roof joists (2). This is used more for retrofit, e.g., when refurbishing an existing timber joisted flat roof which has no insulation. The insulation is below the deck (3) but above the plasterboard (4). It allows insulation to be added without having to replace the waterproofing (5) on the existing roof or raising the roof line. It’s important to make sure that there is at least a 50mm air gap (6) for ventilation above the insulation and the roof deck to prevent condensation occurring.

Question 3

what insulation is needed for IWI?

Answer 3

Rigid board‑PUR, PIR or PF

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Mineral wool batts or wools

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Wood fibre boards.

Question 4

How do you install the PIR boards?

Answer 4

1Image 1 – foam adhesive applied to PIR board to finish off the wall. Smaller pieces should be fitted at the top.

Image 2 – deep fill any remaining gaps between the PIR boards and the wall/floor/ceiling with low expansion foam.

Image 3 – at window and door reveals, pieces of PIR board can be cut so they overlap the insulation on the main wall.

Image 4 – fix wall plug insulation anchors to each board and then cover with aluminium tape over the top of the anchor.

Image 5 – shaping and fitting the PIR to a sloping ceiling.

Question 5

Plaster boArds finish

Answer 5

Question 6

what is the fixing method for custom build EWI projects

Answer 6

Use of both adhesive (image 1) and mechanical fixings (image 2)

Question 7

what do insulation boards need to be protected from?

Answer 7

bad weather

Question 8

When drilling hole for cavity wall what should you do?

Answer 8

When drilling holes through the outer leaf, make sure they do not slope inwards towards the cavity
All drilling must be completed on one elevation and at least 2m of the adjacent elevations before injection commences on that elevation

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Care should be taken when drilling next to building features. It’s advisable to drill at least two courses below such features.

Question 9

Cavity wall insulation - drilling holes

Answer 9

Generally, a cavity wall Insulation system uses 22/25mm diameter holes. The distance between successive injection holes should be a maximum of 1.35m. Where possible, a diamond pattern should be used so that an injection hole in one row is midway between two holes in the rows above and below.

At the tops of walls and under gables, the topmost injection holes should not be more than 350mm below the upper edge of the cavity to be filled. Additionally, under horizontal boundaries, for example under eaves, windows or lintels, the centres between the topmost injection holes should not exceed 1.0m.

Question 10

whats the machinery for cavity wall insulation and who does it have to be approved by ?

Answer 10

The machinery (image left) is specialist equipment and you need to be trained and competent in its use. Here are a couple of pointers.

Each blowing machine is identified as being approved by a plate/label showing the BBA certificate number.

Question 11

how are wool density checked for cavity wall insulation

Answer 11

Density checks are carried out to make sure the machine is delivering the correct weight/volume
This is done by filling a test box and checking its weight, see the image below.

Question 12

How should filling be proceeded for cavity walls?

Answer 12

Filling should proceed from the bottom to the top of walls and from the most to the least restricted sections. Filling from the bottom ensures a uniform fill.
The blowing machine is relatively simple to operate, 1 to 2 bales of wool can be emptied into the hopper at once

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The hopper should always be kept half full

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The feed rate is automatically controlled by a worm screw, and the only necessary adjustments will be to the:

Restrictor plate
Dump valve
Engine revs

Question 13

what do you need to do in order to obtain the correct density fill for injected cavity insulation

Answer 13

insulation should be introduced into each injection hole in turn. Starting at one end of the elevation, and at the bottom of the wall, and working across from side to side

You will get a signal from the pressure switch that de-energises the clutches highlighting hole is full.

Question 14

How do you make good the hole for injected cavity insulation

Answer 14

mortar mix should be made up before the installation begins. That way the preceding holes can be made good while the next hole is filling. It also allows adjustments to be made to the colour match when required.

Question 15

How do you prepare for underfloor insulation?

Answer 15

1. sort out the gaps between the floor and the gaps between the floor and the wall

2.the cables need to be sorted out

3.central heating pipework sealed with silicon

Question 16

Whats the biggest issue of upgrading existing floors?

Answer 16

that it raises the existing floor level by the thickness of the insulation being used, which is usually 50mm.

The other thing to think about is the risk of thermal bridges at the wall/floor junctions.

Question 17

what is plaxing insulation over the existing floor called?

Answer 17

floating floor.
this will impact

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Architraves

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Skirting boards

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Raising the height of the door frame and lintel

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Dealing with the depth of the bottom step of the stair case.

Question 18

what is the typical material used for floor insulation

Answer 18

Rigid plastic foam boards (PIR, PUR or PF)

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Rigid polystyrene (EPS or XPS)

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Rigid natural materials (wood fibre).

Question 19

the check list for underfloor insulation

Answer 19

Work out the material requirements by working out the floor area, and dividing that by the area of the boards you’re using

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Remove any skirting boards, door architraves and doors

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Where the door opening need to be raised, the door casing also needs to be removed

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The work to the door opening (if required) can be prepared at this stage

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Prepare the floor area, make good any defective areas

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You need to check that the floor is level, particularly in older properties, this can be done by using a self-levelling cement compound, see image below.

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Even if the existing floor is damp free, a 1200 gauge polythene damp-proof membrane (DPM) should be laid beneath the insulation first

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The joints of the DPM should be well lapped and taped and taken up the edge of the insulation

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The insulation should be laid in a staggered pattern to prevent any gaps, with the joints lightly butted together

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The joints to the insulation boards should be taped

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The floor finish is then laid over the insulation

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Finally, the joinery items removed at the start are re-fixed or renewed.

Question 20

whats the using of Rigid Vacuum Insulation Panels (VIPs)?

Answer 20

This comprises of rigid vacuum insulation panels with a microporous core which is evacuated, encased and sealed in a thin, gas–tight envelope, giving excellent thermal conductivity and providing the thinnest possible solution to insulation problems.

The vacuum insulation panels are accompanied by rigid thermoset insulation infill panels which can be used where the remaining dimension to infill is below 300mm or can be cut to fit around problem areas such as penetrations or load-bearing walls.

Question 21

What is the installation of the Rigid Vacuum Insulation panel?

Answer 21

Concrete slabs should be allowed to dry out fully prior to the installation of the insulated flooring system

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The surface of the slab should be smooth, flat and free from projections

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Thorough cleaning of the floor and removal of all projections is essential

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A protection layer should be used under the insulation, this will be specified by the manufacturer

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The insulation panels should always be loose-laid, joints staggered where practical, with all joints lightly butted

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Starting at each external corner of the floor, proceed to lay the insulation across the floor area in a break bond pattern with all panel joints lightly butted

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Where runs of insulation don’t accurately fit the dimension of the floor the use of flex trips is required which should be the same thickness as the panels

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A strip of flex strip (minimum 25mm thickness) should be placed vertically around the perimeter of the floor slab in order to reduce cold bridging

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The top of the vertical strip should be level with the top of the floor screed, and the bottom should be level with the bottom of the horizontal floor insulation and closely butted up to it.

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A protection layer may be used over the insulation

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Insulation panels should be overlaid with a separation layer (not less than 125 micron/500 gauge) to prevent the wet screed penetrating the joints between the boards and to act as a vapour control layer. Ensure the separation layer has 150 mm overlaps, taped at the joints, and is turned up 100mm at the walls.