Boarding out the loft question

[User482]

What I did:

1. Fill insulation to the depth of the exiting joists.
2. Screw lengths of 4x2 at right angles to existing joists.
3. Fill insulation to depth of new timbers.
4. Fit loft boards across the top and screw down.

You have a good depth of insulation, and the load is well supported. Make sure any wiring is not buried at the bottom of the insulation. A mask, gloves, goggles and overalls/ paper suit are essential for this job.

 

[slowmotion]

What I did:

1. Fill insulation to the depth of the exiting joists.
2. Screw lengths of 4x2 at right angles to existing joists.
3. Fill insulation to depth of new timbers.
4. Fit loft boards across the top and screw down.

You have a good depth of insulation, and the load is well supported. Make sure any wiring is not buried at the bottom of the insulation. A mask, gloves, goggles and overalls/ paper suit are essential for this job.

Good advice. If you only have 6 amp lighting circuits in your loft, they will probably have been clipped to the top of the original ceiling joists if your home is pre-Seventies. The informal consensus is that you can put 170/200mm of extra Rockwool over them with very little risk.

Here's why I believe this..... I was involved in an HMG survey of "before and after" energy consumption in 100 dwellings where insulation was retro-fitted. It involved crawling around in a lot of lofts. In every instance, the contractors had just lobbed rolls of 170mm insulation at right angles to the existing joists. None of the sample dwellings had re-routed electrics.

 

[pclay]

Loft legs. I boarded out my 1930s 3 bed semi using loft legs, last year. I did it on my own and it took several months. But I was a bit anal about it. I removed all the insulation, vacuumed out the loft (lather and plaster ceilings) put the legs in with tounge and groove chipboard on top. I didn't do it all in one go, I did it bit by bit.

It helped that my loft has a velux window which can open. The area I boarded is the same footprint as the house, so a large space. Electric cables were run under the joists, so there was no way I was getting them out. Besideas all my lighting is led now, so the cables have minimal loading. I will post a pic later.

 

[ryan_w]

Remove old insulation and fit something like a Kingspan product.

A 22mm tongue and groove floor system will actually insulate it more than you'd think.

Is there insulation between the rafters or just a membrane?

 

[slowmotion]

Remove old insulation and fit something like a Kingspan product.

A 22mm tongue and groove floor system will actually insulate it more than you'd think.

Is there insulation between the rafters or just a membrane?

Isn't Kingspan based on rigid polyurethane? It's eye-wateringly expensive compared to a few rolls of Rockwool from Wickes.....(on special offer at the moment BTW..)

 

[screenman]

Wingspan is very expensive compared with Rockwall, I have a lot of it in this house and my garage. 9 years ago I was paying £17 a sheet for 125mm now £55 I think.

I did my 7x7 garage for only £100 using second hand 100mm.