Building up joists for laying insulation

[DRG1]

Hi all

First post and all.

Sure this is covered somewhere, and maybe should be under woodwork?

I am going to lay some insulation over the existing old insulation between the joists. However, I first obviously need to build the joists up. First question is can I rather than use whole pieces of timber just put smaller bits on e.g. 30cm with 30cm gap etc. then lay insulation and screw boards on?

Second, and I know this is stupid - what is the best way to attatch the built up joist, i.e. join the new to exisiting bit? should I use some metal brackets or something?

Cheers

Andy

 

[Johnmelad502]

Why build the joists up?

 

[ladylola]

Hi all

First question is can I rather than use whole pieces of timber just put smaller bits on e.g. 30cm with 30cm gap etc. then lay insulation and screw boards on?


Cheers

Andy

When you say "screw the boards on" do you mean that you are going to be fixing flooring to enable the space to be used as a room or for storage?
If it's just insulating that you're doing then as John says why build up the joists?

 

[DRG1]

sorry, should have made that clear, yes i am going to put boards on to get all the rubbish out the front bedroom and into the loft!

 

[ladylola]

How much will you be building up the joists?
It's better to use a continous piece of timber if possible. Firstly put some tempoary props underneath the ceiling to stop the sag when you're working up there. ( I'm not saying you are fat but there will be deflection which you don't want to build in).Assuming you are building up by around 3" drill a hole through the timber to take a screw, all of this can be done outside of the loft. You may need to drill a larger hole part of the way in to allow say 4" screws to penetrate the original joists sufficently. PVA glue can also be used where the timbers meet and for added strenght fix pieces of ply glued and screwed onto the sides of the now built up joist. These pieces don't need to be continous.
When I did my house I had two 7" summer beams to build up to so I followed the above method with 3" x 2" 's and then 4" x 2" 's placed at 90 degrees and joist hangered to the beams. Where the timbers crossed I tied them with 2"x2" 's placed vertically.