I have looked at the options for strengthening the joists in our loft
before boarding it and have decided that for our situation gluing and
screwing new 4"x2" over the existing is the way to go. My one one
concern is if the new wood shrinks (as I believe it is likely to) it
will cause the whole new joists to bend, I don't think it would have
to shrink very much for the change of shape to be quite significant.
Has anyone done this? Do I have some way of ensuring that the wood
that I buy is fully seasoned?

Thanks

Brendan.

On 26/04/2012 13:11, Rednadnerb wrote:
I have looked at the options for strengthening the joists in our loft
before boarding it and have decided that for our situation gluing and
screwing new 4"x2" over the existing is the way to go. My one one
concern is if the new wood shrinks (as I believe it is likely to) it
will cause the whole new joists to bend, I don't think it would have
to shrink very much for the change of shape to be quite significant.
Has anyone done this? Do I have some way of ensuring that the wood
that I buy is fully seasoned?

Thanks

Brendan.

The CLS stuff they sell for studding etc is kiln dried IIRC.
It's not going to shrink much, especially if the loft is unheated

Rednadnerb wrote:

I have looked at the options for strengthening the joists in our loft
before boarding it and have decided that for our situation gluing and
screwing new 4"x2" over the existing is the way to go. My one one
concern is if the new wood shrinks (as I believe it is likely to) it
will cause the whole new joists to bend, I don't think it would have
to shrink very much for the change of shape to be quite significant.
Has anyone done this? Do I have some way of ensuring that the wood
that I buy is fully seasoned?

Thanks

Brendan.

Use plywood?


--
Tim Watts

Use plywood?

--
Tim Watts

How do you mean? built up in layers to add another 4 inches?

Rednadnerb wrote:


Use plywood?

--
Tim Watts

How do you mean? built up in layers to add another 4 inches?

No -I mean use plywood which should not shrink.


--
Tim Watts

On 26/04/2012 15:53, Tim Watts wrote:
Rednadnerb wrote:


Use plywood?

--
Tim Watts

How do you mean? built up in layers to add another 4 inches?

No -I mean use plywood which should not shrink.



Sounds as though the OP is insulating the rafters, so presumably there
is no point in raising the floor level by 4". Ply would be ideal if, for
some reason, the floor needs strengthening

On Apr 26, 1:11*pm, Rednadnerb wrote:
I have looked at the options for strengthening the joists in our loft
before boarding it and have decided that for our situation gluing and
screwing new 4"x2" over the existing is the way to go. My one one
concern is if the new wood shrinks (as I believe it is likely to) it
will cause the whole new joists to bend, I don't think it would have
to shrink very much for the change of shape to be quite significant.
Has anyone done this? Do I have some way of ensuring that the wood
that I buy is fully seasoned?

Thanks

Brendan.

Another way to strenghten the floor in a loft, if there is purlins, is
to screw some bits of wood on top of the joists parallel to and under
the purlins and put in hangers between the purlins and your new bit of
wood.
The hangers could be part of your wall too.

On 26/04/2012 16:36, harry wrote:
On Apr 26, 1:11 pm, wrote:
I have looked at the options for strengthening the joists in our loft
before boarding it and have decided that for our situation gluing and
screwing new 4"x2" over the existing is the way to go. My one one
concern is if the new wood shrinks (as I believe it is likely to) it
will cause the whole new joists to bend, I don't think it would have
to shrink very much for the change of shape to be quite significant.
Has anyone done this? Do I have some way of ensuring that the wood
that I buy is fully seasoned?

Thanks

Brendan.

Another way to strenghten the floor in a loft, if there is purlins, is
to screw some bits of wood on top of the joists parallel to and under
the purlins and put in hangers between the purlins and your new bit of
wood.
The hangers could be part of your wall too.

I am just trying to think out the box, but what if the `new` 4 x 2 was
only screwed to the existing joists but with pre drilled holes in the
new ones that were oval or elongated and the screws just tight enough to
hold them in place then would this allow sufficient movement for any
shrinkage without ditorting the original joists. They could be fully
tightened at a later date after any shrinkage has taken place.
Dont know if it is practical but just my thinking.

On Thursday, April 26, 2012 1:11:12 PM UTC+1, Rednadnerb wrote:
I have looked at the options for strengthening the joists in our loft
before boarding it and have decided that for our situation gluing and
screwing new 4"x2" over the existing is the way to go. My one one


why not lay the new joints on top of the old and leave them there for a couple of months. Then they will attain the moisture content appropriate to their position and you can glue them on. Its lengthways shrinking yo uare concerned about - that's in any case much less than shrinkage across the grain.

You are doing this for strength, but are you sure that gluing a second joist on top will meet that need? I am a bit surprised. I thought one normally laid a full sized joist next to the old one. Have building control approved the method?

Robert

I am just trying to think out the box, but what if the `new` 4 x 2 was
only screwed to the existing joists but with pre drilled holes in the
new ones that were oval or elongated and the screws just tight enough to
hold them in place then would this allow sufficient movement for any
shrinkage without ditorting the original joists. *They could be fully
tightened at a later date after any shrinkage has taken place.
Dont know if it is practical but just my thinking.

It's an interesting idea but I will be boarding over the joists
immediately.

Another way to strenghten the floor in a loft, if there is purlins, is
to screw some bits of wood on top of the joists parallel to and under
the purlins and put in hangers between the purlins and your new bit of
wood.
The hangers could be part of your wall too.

That would be good but I want the floor space to be available from
eaves to eaves, no walls.

I think CLS timber is the tip that I have been looking for. Just need
to see if I can find it in 5 metre lengths.

Thank you all.

Brendan.

On 26/04/2012 18:50, Rednadnerb wrote:
I think CLS timber is the tip that I have been looking for. Just need
to see if I can find it in 5 metre lengths.

Thank you all.

Brendan.


Could you get 5 metres into your loft?

On Apr 26, 6:50*pm, Rednadnerb wrote:
I think CLS timber is the tip that I have been looking for. Just need
to see if I can find it in 5 metre lengths.

Thank you all.

Brendan.

I think you want KD. CLS is KD, but also meets other unnecessary
specs. Practically speaking it neednt necessarily be C16 rated, as you
already have enough sound wood in place.

It'll be fun getting 5m thru the hatch


NT

On Apr 27, 1:43*pm, NT wrote:
On Apr 26, 6:50*pm, Rednadnerb wrote:

I think CLS timber is the tip that I have been looking for. Just need
to see if I can find it in 5 metre lengths.

Thank you all.

Brendan.

I think you want KD. CLS is KD, but also meets other unnecessary
specs. Practically speaking it neednt necessarily be C16 rated, as you
already have enough sound wood in place.

It'll be fun getting 5m thru the hatch

NT

Yes you are right. I was in Selco today and everything seems to be
kiln dried already. Seems I was worrying needlessly.
I'll probably take a few tiles off the roof somewhere to get them in.

Thanks all.

On 27/04/2012 21:23, Rednadnerb wrote:
I'll probably take a few tiles off the roof somewhere to get them in.

Or above a window cut a hole in the ceiling and slide them in through
window and ceiling and patch ceiling afterwards.