Loft Boarding Advice

Danny30

Hi, I just got a loft hatch and ladder installed and am now looking to get my loft boarded or mostly boarded depending on costs. I want to make sure that the joists are very strong before boarding as don't want to worry all the time about weight.  also have a water tank up there so assume loftmight be relatively storing already?

My loft is around 650cm length by 350 cm width with 4 x 2 joists and around 40cm from joist to joist. 

I was thinking of attaching timbers along the current ones to strengthen the joists further and then do do add joists across those to raise the joists to allow for the insulation. 

Does this sound like a reasonable idea, or is it overkill perhaps?

I am also trying to work what timber I need for the joists and how many would be required to complete the project. I was thinking of getting 4 by 2 joists at 300 cm lengths so would need:

To strengthen Existing boards (650cm length of loft)

650cm length of loft / 300cm joists = 2.16 Timbers per joist

350 cm width of loft  / 40cm (space between joists) = around 9 Joists currently covering the loft

so 9 joists x 2.16 timbers per joist = around 20 Timbers to strengthen current timbers in loft.



For new timbers to raise loft boards (350cm width of loft)

650cm length of loft  / 40cm (spacing from joist to joist)  = 16.25 new joists needed
 
16.25 joists x 3.5m  (width) = 56.87 metre of timbers

56.87 / 3 metre timbers = around 19 timbers

So total around 20 + 19 =  39 Timbers for joists. Does that look correct?

I am a bit confused to be honest now lol, not sure that even makes sense.

FreeBear

Which direction are the joists ?

Assuming they span the 3.5m, 4x2 is plenty for a loft floor used for storage - I'd fit some loft legs, fill the space with insulation, and then fix boards over the top.

If you are wanting to use this space as a loft conversion, then you will need bigger joists installed appropriately on suitably sized bearers. That could mean 8x2 joists (and no, you can not stick 4x2 on top of the existing timbers) and perhaps some steels either side to stop the walls from spreading - Structural engineer territory, and you may well want to involve building control.

GDB2222

I think that you are over worrying about this.  But can I ask some details.

Which way do the joists run, ie are they 3.5m long or 6.5? 

Are the joists supported by walls underneath.

what are you planning to do up there? Just store some junk, or have a big party with 50 people all jumping up and down at the same time? 

For the insulation, you can get some legs to screw to the joists, then put the boards on top of that.  

GDB2222

It looks like Freebear and I have asked the same questions in different ways.

Danny30

GDB2222 said:

I think that you are over worrying about this.  But can I ask some details.

Which way do the joists run, ie are they 3.5m long or 6.5? 

Are the joists supported by walls underneath.

what are you planning to do up there? Just store some junk, or have a big party with 50 people all jumping up and down at the same time? 

For the insulation, you can get some legs to screw to the joists, then put the boards on top of that.  

FreeBear said:

Which direction are the joists ?

Assuming they span the 3.5m, 4x2 is plenty for a loft floor used for storage - I'd fit some loft legs, fill the space with insulation, and then fix boards over the top.

If you are wanting to use this space as a loft conversion, then you will need bigger joists installed appropriately on suitably sized bearers. That could mean 8x2 joists (and no, you can not stick 4x2 on top of the existing timbers) and perhaps some steels either side to stop the walls from spreading - Structural engineer territory, and you may well want to involve building control.

Thank you for the replies. The joists run length ways(6.5m)  so span the wider part of the loft. 

I am planning to use for storage but may want to put a workbench or do some DIY up there possibly. 

How can tell if loft is supported by walls underneath? 

Is it better to use 2400 boards instead of 1200 due to less loft legs needed? 

Danny30

Looking at loft legs they would cost around £17 for 12 pack and I would need around 12+ packs at least so £340 for just loft legs. Timber seems to be much cheaper. 

FreeBear

A floor plan can give us some clues as to where there might be supporting walls. It would be unusual to have a 6.5m span of 4x2 timbers without any additional support, even if it is only a stud wall below.

Wait until you see the price of timber before you decide loft legs are too expensive - 1.2m boards will be fine. You'll still need the same amount of support regardless of the length of boards (typically, 400mm centres).

plumb1_2

Depends on what size boards you can get through the hatch 

Danny30

plumb1_2 said:

Depends on what size boards you can get through the hatch 

The hatch is 113 cm x 55cm

GDB2222

Danny30 said:

plumb1_2 said:

Depends on what size boards you can get through the hatch 

The hatch is 113 cm x 55cm

The space above the hatch matters too. And the ladder may be in the way. 

Smaller boards are easier to handle, especially if you don’t have help.