Sacrificial wood for temporary roof

[LSB]

We are DIY Self building in 3 phases, over many years.

Phase 1 walls are finished with a temp roof, made from the old barn roofing sheets with the final posi joists as this is a separate roof.

 

We are now looking at doing the same for phase 2, but we don't want the final posi-joists as the whole roof needs to be done in one hit.

 

Does anyone know a good place to get 4*2 timber for joists that will ultimately become firewood.

they do need to be long long, one side is 4m and the other side 6m. 

I will need about 25 of each length.

These are partly to brace the walls until we are ready for whole roof and partly to allow us to store equipment which is currently in another part of the barn.

 

Any suggestions greatly received.

 

TIA Jill

 

[Nickfromwales]

8 hours ago, LSB said:

We are DIY Self building in 3 phases, over many years.

Phase 1 walls are finished with a temp roof, made from the old barn roofing sheets with the final posi joists as this is a separate roof.

 

We are now looking at doing the same for phase 2, but we don't want the final posi-joists as the whole roof needs to be done in one hit.

 

Does anyone know a good place to get 4*2 timber for joists that will ultimately become firewood.

they do need to be long long, one side is 4m and the other side 6m. 

I will need about 25 of each length.

These are partly to brace the walls until we are ready for whole roof and partly to allow us to store equipment which is currently in another part of the barn.

 

Any suggestions greatly received.

 

TIA Jill

 

If your proposed future roof needs parallel chords of a posi joist, at lengths like 6m, then you have zero chance of running a 4x2 for that distance, singularly, as nobody stocks them afaik; they’d be too weak also. 

For my current client I have had to sister 2x 4x2’s to get beyond 3.6m;  single 4.8’s are possible, but are weak and useless. For s roof, forget it basically. 

 

Posi joists are cheap enough, so wasting time, effort, money the way you propose is a bit ‘non cost-effective’ and methinks wholly impractical. 

[Redbeard]

Agree with @Nickfromwales, but if you do still want an 'interim' solution what about the longest 50x50 sawn you can get - probably 4.8 or 5.1 x 2 with ply or OSB between, as 'quasi I-beams'? 2 x 2 will come in useful in its own right or glued and screwed as 4 or 6 x 2.

[LSB]

WE are vey slow building, think Pocster 🙂

 

So, although temp for storage realistically it needs to last probably 2 year.

 

this shows how the roof was done previously when built in the 60's.

 

We will be using the same roofing sheets, but the wood is pretty much knackered.

 

We just want to replicate this as cheaply as possible for dry storage, the roof material is very light as just rain cover.

 

This is all held together with joist hangers but we were hoping to do wall plates and joists.

 

The issue is that roof one (not there in this picture) is 4.2m including the walls and roof 2 is 5.4m.

 

For what we need we are happy to 'join' joists to make the spans from 3.6m sections, but that means for the phase we are doing we will need 64 joists plus wall plates which potentially might not survive being left for years.

 

Phase 3, which is the bit you can see until the blue barrel behind the wheelbarrow will not have a temp roof.

Once that is finished then the whole lot will be done properly with the posi-joists.

 

 

 

[Nickfromwales]

4.2 and 5.4 spans, or width?

 

If spans, then you’ll need minimum 5x2 even foe a temporary offering, or you could install a perpendicular ‘spine’ mid span made of 2x 6x2’s bolted together, then you can use 4x2 to span wall > spine > wall easily.

 

By the time you sheath this, minimum 18mm OSB, there will be a lot of weight up there.

 

And most self builders mean 3 or more years when they say 2 .

[LSB]

6 hours ago, Nickfromwales said:

4.2 and 5.4 spans, or width?

 

If spans, then you’ll need minimum 5x2 even foe a temporary offering, or you could install a perpendicular ‘spine’ mid span made of 2x 6x2’s bolted together, then you can use 4x2 to span wall > spine > wall easily.

 

By the time you sheath this, minimum 18mm OSB, there will be a lot of weight up there.

 

And most self builders mean 3 or more years when they say 2 .

This is the span, the width of this phase is 13m, the total width will be 24m.

 

There are 2 spans as the middle wall will be the end of one bit of roof joist and the start of the other one, but the roofing sheets will be continuous, if we have enough long ones left from the barn, if not then overlapped.

 

Low and wide.

[Russell griffiths]

If you have half a building up I would roof the lot completely not temporary. 
get all the posi joists

sit them on the walls you have built, sail the sheets over the bit you haven’t built and hold the wall plates up on 4x4 posts, then build the walls up under cover, will help you when the winter comes. 

 

[scottishjohn]

On 08/08/2026 at 17:30, Russell griffiths said:

If you have half a building up I would roof the lot completely not temporary. 
get all the posi joists

sit them on the walls you have built, sail the sheets over the bit you haven’t built and hold the wall plates up on 4x4 posts, then build the walls up under cover, will help you when the winter comes. 

 

I agree  don,t do any more till you can afford to put a proper roof on it 

 

 why spend twice in money and labour 

then you will have a dry bit to work away as time allows

 

 have same problem with my next phase of rebuilding  some stone buildings 

 

 and decided might as well just it right once --then work away with the insides

 

 a piccie of my ruin which is attached to rebuilt house

[LSB]

On 08/08/2026 at 17:30, Russell griffiths said:

If you have half a building up I would roof the lot completely not temporary. 
get all the posi joists

sit them on the walls you have built, sail the sheets over the bit you haven’t built and hold the wall plates up on 4x4 posts, then build the walls up under cover, will help you when the winter comes. 

 

 

I will tell hubby this, but he probably won't agree 🙂

This is what we did on the small roof, the posi joists are in place with temp sheets.

 

[LSB]

We've been discussing this and like everything with building we are hitting a catch 22 situation.

 

There are 3 parallel walls with one end wall at the moment to the East (phase 2).

Phase 3 is still with the old single skin walls and concrete which all needs to be broken out and dug down to the right level which is about 1m+

Then the founds need to be poured down to 'good' soil which may be 2.5m + due to some clay.

 

Our concern is that the 3 walls that have been done could potentially, without being braced, be unstable until the other end is done.

 

This is not ideal but was the only option with renovating and underpinning.

 

So, snug / hall are complete with posi roof and temp covering.

 

The South wall (bed 3 right), East wall are done and North wall is under construction.

 

But we then need to underpin bed 4, pantry, utility and West family wall (yes it does have the kick back from the barn)

 

We want to brace the North to middle wall and the middle wall to South wall, the roof joists will be resting on the middle wall.

 

the distance North to middle is 5.4m and middle to South 4.2m

 

It is single storey.

 

South is 11 blocks and North is 14 blocks, so difference is 3 blocks (not 2) so should be okay for roof slope and draining.

Snug / Hall have their own roof which is lower than the height of the North wall.

 

The striped walls are solid and existing, the pink ones will be stud walls and could move.

 

The posi joists are made to measure allowing for the slope so we aren't keen on ordering the full one until we know the exact measurements.

We have it specified and quoted, but don't want to say go until we are sure.

Phase 3 (utility / family / pantry / bed 4) won't be built until spring / summer 2027 hence why we don't want to leave the other walls swaying in the wind until then.

This phase 3 still has the existing roof which we use to protect saws, excavator, dumper etc so ideally we have the temp roof on master / office to protect from the rain.

 

This is our catch 22 , without finishing we can't measure accurately, so we might have to pay for sacrificial joists just to brace the 3 walls, but that is expensive.

 

Our site is windy and we did lose part of the North wall when it was 5 blocks high between some of the external doors in a gale last winter so we are not just panicking for nothing.

It had not got to the stage of being braced, but the door wooden frames were in situ, but not to lintel level.

 

Maybe this explains a bit more.

 

Our BC and architect were all for knock down and build from scratch, but after spending over 4k on planning to do this (on top of already having spent 6k+ to get conversion planning) we gave up.  The reason for refusal was that it was a new build in the countryside, even though we had planning to convert the barn.  I understand that now it would be easier, but that ship has sailed.

 

So, I hope this explains our predicament a bit more.

 

i know that if we had contract builders it wouldn't be such as issue as it would be quicker, but as DIY these walls need to stand for another winter.

 

 

 

So, suggestions greatly received.

 

Thanks for all your comments so far.

 

 

[scottishjohn]

26 minutes ago, LSB said:

Our site is windy and we did lose part of the North wall when it was 5 blocks high between some of the external doors in a gale last winter so we are not just panicking for nothing.

It had not got to the stage of being braced, but the door wooden frames were in situ, but not to lintel level.

Ok

 

 so presuming you have a suitable concrete floor -- put some fixings in there to secure  temporary wall braces from floor and to the walls  and plastic sheet the walls with a staple gun  to keep the worst of the weather off them  ?  

 sounds like an afternoons job

 if as you said a five block high wall fell over -- then got problems with the cement mix you are suing for the walls --too lean by a long way -- and i would not be happy continuing  with any wall building till you alter the mix ratio  -- me I use 4-1 minimum

Edited 3 hours ago by scottishjohn

[LSB]

1 hour ago, scottishjohn said:

Ok

 

 so presuming you have a suitable concrete floor -- put some fixings in there to secure  temporary wall braces from floor and to the walls  and plastic sheet the walls with a staple gun  to keep the worst of the weather off them  ?  

 sounds like an afternoons job

 if as you said a five block high wall fell over -- then got problems with the cement mix you are suing for the walls --too lean by a long way -- and i would not be happy continuing  with any wall building till you alter the mix ratio  -- me I use 4-1 minimum

Thanks,

The wall that fell over was the old one that had been there since the 1960's and was a farm building so we've no idea of the make up.  We were supposed to use the old ones as a conversion just with a 2nd cavity wall.

To be honest we weren't that disappointed as it meant it could be done to modern standards 🙂

It was rebuilt before anyone came and saw it so looks just like the old one.

 

This was just to demonstrate the winds that we can have being at the top of a hill with no protection.

Nothing like Scotland I don't expect though 🙂

 

I've no idea what mix we are using now, I'll ask when I see 'the builder' aka hubby.