Loft Preparation - Insulation

Drawing of construction details.

The plan was to use additional battons to strengthen the existing rafters, and to make up the depth so that more insulation could be used. The floor boards could then be laid on top.

I am laying 150mm of insulation. It comes in rolls of 100mm and 50mm. I am laying the 50mm perpendicular to the 100mm to lower head transmission through the original rafters.

Dimensions
25mm by 50mm batten on top of existing rafter.

Here are new 25mm battons have been screwed to the existing 75mm (or 3 inch when the house was built) beams. The first 100mm of insulation can then be laid.

When screwing down the battons the position of any screws or nails in the old rafter were noted as they were being covered up. This was to prevent me later trying to drill a hole for another screw at the same point. The screws and nails could not be removed as they were holding the ceiling together.

Note showing the location of a hidden nail.
25mm by 50mm battens running perpendicular to existing rafters.

The extra 50mm of insulation can now be laid. Most of the battons are 50mm by 25mm. To support the ends of the floor boards, battons 50mm square are used.

The perpendicular battons are held in position, and upright, by 40mm brackets. The force from somebody standing on the floor will be transmitted to the beam below as the batton is resting on it. Eg. the bracket does not take the weight. The end battons were screwed directly to the original perpendicular beam.

Single bracket holding batten.
Pair of brackets holding batten.

The last intersect of two battons before the end of a batton (just out of shot) were held with two brackets to ensure the batton stayed upright.

The 50mm square battons could stay upright with fewer brackets because of their additional width.

50mm by 50mm batten held with a bracket.
Bracket held with 3 screws.

Even with careful marking out (measure twice, cut once) some of the holes did not match up. My power drill is too big to drill a new set of holes with the batton already in position.

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