Attaching joists to existing bearers.

[BetweenNightAndDawn]

I posted this thread the other day, having not understood what bearers are: https://www.diynot.com/diy/threads/strengthening-loft-for-storage-and-light-use.558668/

Would it be permissible sister each bearer with two additional 6x2s, bolted at the ends where the bearers meet the wall, with 18mm of padding so that they're not touching?

I can then add my 5x2s at cross sections to these new timbers with joist hangers and noggins, pretty much creating a new floor above the existing 4x2s.

I'm trying to weigh up strength vs. depth for insulation vs. not disrupting the current floor or doing anything dodgy! The floor will need to support storage and two people sitting up there watching a film from time to time, but we're not planning on having parties or anything like that.

If anyone knows of any other options outside doing a full loft conversion (which isn't necessary for us), that would be great.

On that note, I had a look at LoftZone, but it stipulates that it is strictly for storage only. Apparently it supports up to 500kg per square metre though, so it might be an option considering the existing 4x2s seem sturdy and it spreads the weight out.

 

[regsmyth]

Are the 6x2's built into the walls at each end? Would you be able to get a full length timber (approx 4.5m?) into the space?

 

[BetweenNightAndDawn]

Thanks for the reply regsmyth. Yeah they're inside the wall at both ends, but there is no space to put another timber in there and making the space bigger is beyond me.

From what I've read if I were to bolt as close to the wall as possible, most of the weight would be spread to the wall rather than the length of the bearer itself? There's a lot of advice about sistering joists and bolting those at the wall ends, but that's not really an option for me because of the bearers being in the way.

 

[regsmyth]

No I meant can you physically get 4.4m long timbers upstairs and into the loft?
If you can, then your idea seems reasonable to me, but I'm no expert.
However, you'll also need to add a 6x2 on top of the 4x2's at the eaves.... or better maybe just a 2x2 with your 5x2's notched and resting on top. Ditto at the middle.
Whether it's permissible, sensible or advisable...well what's the worst that can happen?

 

[tony1851]

I wouldn't like to be standing below your loft if you're going to support 500 Kg per sq m. up there.

 

[BetweenNightAndDawn]

No I meant can you physically get 4.4m long timbers upstairs and into the loft?
If you can, then your idea seems reasonable to me, but I'm no expert.
However, you'll also need to add a 6x2 on top of the 4x2's at the eaves.... or better maybe just a 2x2 with your 5x2's notched and resting on top. Ditto at the middle.
Whether it's permissible, sensible or advisable...well what's the worst that can happen?

Yeah we can get them up there, the loft hatch is thankfully in a reasonably long hallway! Would the 2x2s on top be for the gap for insulation or strength? Cheers.

 

[BetweenNightAndDawn]

I wouldn't like to be standing below your loft if you're going to support 500 Kg per sq m. up there.

Haha, we won't be storing anything near that much (sounds like a gym!) I just noticed that's what LoftZone claims it can take, but would be equally concerned if we we storing that much stuff.

At most it will be a maximum of 150kg of 'stuff' in total. Then on occasion, me and my wife watching a film on a wall mounted projector.

So basically, the floor needs to be strong enough to store 75kgs of stuff on both sides all the times, plus from time to time house two humans watching a film on a fold out sofa in the middle portion of the loft.

My idea might be overkill and something like LoftZone might be enough to do what I want to do (considering it evenly distributes the weight and the joists don't have a lot of spring in them at all). I've found a couple of posts where people have used it for a model railway room, which weight wise doesn't sound dissimilar for what I'm after (I'm just not sure so wanted to canvass opinion before I do anything).

 

[regsmyth]

The 2 x 2 would rest on top of and run perpendicular to the current 4x2's along the eaves. Your new 5x2 joists would be fixed to your new 6x2 at one end and rest on top of the 2x2 at the eaves end. If the top of the 5x2 is level with the top of your new 6x2, you would have to notch the end of the 5x2 to keep it level. Or if you put your new 6x2 an inch higher than your existing bearer, no notching required.

 

[BetweenNightAndDawn]

The 2 x 2 would rest on top of and run perpendicular to the current 4x2's along the eaves. Your new 5x2 joists would be fixed to your new 6x2 at one end and rest on top of the 2x2 at the eaves end. If the top of the 5x2 is level with the top of your new 6x2, you would have to notch the end of the 5x2 to keep it level. Or if you put your new 6x2 an inch higher than your existing bearer, no notching required.

Sorry misunderstood. That makes sense, cheers!