Laminating loft joists

[newbuyer17]

I have an existing loft with beams/joists 2inch by 3inch, with boards over and used for light storage.

Full width of house is about 7m, with brick supporting wall half way across, so weight bearing span of each joist is about 3.5m.

From what I've read these joists are not really adequate for putting any weight on them. Additionally, I'd like to get some decent insulation under the boards.

I initially planned to put sister joists of 6" by 2" next to these and put the boards onto them, with 6" insulation underneath,

However, it has been suggested to me that laminating the existing joists is the easier option. By this I've been advised to add another 2" by 3" beam on top of the existing ones, and screw them together.

Can anyone advise whether this will work and give the same strength as a single 6*2 beam, and also exactly how to do it i.e. what size screws, gaps between screws, whether to use glue as well?

What is this process called - "laminating joists" doesn't seem to return much in a search engine so not sure if it has a different description.

Note that this is for storage only - it isn't ever going to be turned into a room so building regs dont apply.

Thanks

 

[geraint]

so what is laminating.......

 

[flameport]

While you could do as you suggest, it seems to be a huge amount of expense and effort for little or no gain.

The existing joists are not adequate for any substantial weight - simply because they were not designed for that. However just how much weight were you intending to put up there - thousands of houses have similar loft construction, and no problems with putting a few boxes or whatever up there.

Boarding the floor will add a significant weight loading to the joists in itself, and therefore reduce the weight of stuff you can store in there.

6 inches of loft insulation is half the recommended amount.

 

[hotrod]

The term you're looking for is 'glulam'.

 

[^woody^]

It is not laminating. Laminating is bonding and gluing like plywood. Glulam is a process of gluing multiple timber sections to form beams - but is not like fixing one 3x2 on top of another

Fixing 2x 3x2's does make it as strong as a 6x2 but will be good enough for your purpose - although you may crack the ceilings if not careful

1 x 5" nr 10 or 12 screw every 500mm. No need to glue, no advantage

 

[newbuyer17]

Thanks all.
What is the 'proper' option then? A whole new bigger beam side by side with the old ones presumably?

I suppose it will cost slightly more with materials, but effort wise will be about the same.

As for insulation, I dont need to get it quite to regs level, and anything is much much better than what is up there now.

Thanks

 

[big-all]

as long as you realise what you are doing will not contribute to a loft conversion in any way in fact it will be a hinderance and add additional cost
so if you plan on doing a loft conversion later them keep this in mind

 

[Deluks]

Big-All makes the most important point here.

So taking that onboard...6x2's screwed alongside existing would stiffen it up nicely for storage purposes. As for insulation, if you were to put down standard 100mm loft wool, with a higher performance insulation such as celotex or kingspan on top, then that would improve the insulation value slightly. The boards could sit between the 6x2's, on top of the 3x2's for support, and then boarded over.