Carcassing timber – can I use sawn

Can I use sawn timber to build a carcass (1.4m tall) that will stay broadly square, like this stuff, from Alsfords:

3.0m Sawn & Treated 45 x 45mm Regularized Carcassing – Plane & Simple (itsplaneandsimple.com)

or do I need to use something more like this

Wickes C16 Treated Kiln Dried Timber – 45 x 70 x 3000mm | Wickes.co.uk

needs to be treated.

What are you building? Planed timber is a more accurate shape and dimension.

They both look the same to me apart from the first one has had the arrises taken off, which is standard for regularised timber. Both are carcassing timbers. What are you going to line it with?

It’s to build a frame to put foam core tile backerboard onto and then tile with interlocking pvc tiles.

https://www.thisiswholesale.co.uk/next-day-building-material-supplies-uk-stock-wholesale-construction/tile-backer-insulation-cement-backing-hard-rigid-board-wall-floor-6mm-10mm-12mm-tile-adhesive-board?gad_source=1&gbraid=0AAAAApX3OczRRILz-Zly_5B-7Yio1guHM&gclid=EAIaIQobChMIsa7slb_oiAMVVplQBh0B-gItEAQYASABEgK16vD_BwE

So I assume that it will be free standing rather than against an existing wall, otherwise battens would seem to make more sense.

If it’s free standing I don’t know how you are tying the ends in/making them stable but I would go for the wider 70×45 rather than the 45×45

@ernielynch each upright will be secured top and bottom but not in the middle, so needs to have some level of rigidity I think. Can you give a linky for treated battens you have in mind?

Regularised timber will be easier to work with, might cost a few quid more, but worth it.

Sounds like a job for 3 by 2. (70 by 45) SCANT or CLS are the two standards. You builders merch will stock one of the two. You shouldnt need treated. If waters getting thru your tiles then timber treatment is the least of your worries.

It’s going to be in a outbuilding that isn’t going to be heated all year round so whilst shouldn’t be exposed to the elements I figured treated might be safest.

Regularised timber could still be rough sawn? The 2×2 i was initially thinking of getting is advertised as regularised but not as kiln dried.

2×2 will be too flimsy though?

Built a few sheds for machinery and timber products and have just used 3″x2″ straight off the mill for partitions, shelves and  cupboard frames or 6″x2″ if it was a load bearing partition between firewood bays or to hold racking.

Any timber should be fine undercover, Larch, Douglas Fir, and Sweet Chestnut have some natural resistance as no one can be bothered with having to apply finishes. Have seen these timbers reused from one shed to the next.

Can you give a linky for treated battens you have in mind?

No it was only if the studwork was going to be against an existing solid wall that something like 2×1 battens might have been suitable.

2×2 will be too flimsy though?

You would get away with it as it will only be 1.4M high but  I would definitely go for 3X2, More solid and stable and imo easier to work with.

As for regularised v ordinary sawn I would select the timber myself and just go for whatever is straighter, IME CLS/regularised timber can be bent and twisted to appalling degrees, whilst ordinary sawn timber can be extremely straight. It just depends and you can’t really be sure until you see it.

Obviously 3X2 ie 75X50  sawn will  be a tad chunkier than 70X45 regularised.

Sawn timber is also likely to be far wetter than CLS/regularised which should be bone dry. That might be an issue if you are cutting by hand rather than cutting using an electric chop/mitre saw. Obviously you will see when you select it.

ok so 3×2 it is. I’m guessing £7.5 for 3m is probably on the toppy end of prices?

Well if it’s the Wickes price it definitely will be I would have thought. It’s worth shopping around, especially with smaller independents, as timber prices can vary significantly. The big boys like Jewsons can be very expensive for a DIY person who is only going to buy small quantities, I’m no expert on material buying but I suspect that they make their money selling very large quantities heavily discounted to large contractors.

Find a local independent where everyone gets the same price e.g.

https://www.savoytimber.com/cls-timber-63mm-x-38mm-3inch-x-2inch.html

https://www.cwberry.com/cls-timber-3000-x-63-x-38mm

Saying that, some of the B&Q CLS isn’t too crazily priced.

As for regularised v ordinary sawn I would select the timber myself and just go for whatever is straighter, IME CLS/regularised timber can be bent and twisted to appalling degrees, whilst ordinary sawn timber can be extremely straight. It just depends and you can’t really be sure until you see it.

+1, 100%, etc.

You’ll get some appalling rubbish if you’re not careful. Rest one end on the ground and sight along it at eye level, twist 90 and repeat. Don’t be afraid to reject lengths, including those that are full of knots.

And take a saw. Timber merchants will charge to cut a longer length down to fit in your car :)

Seems like the perfect opportunity to buy a cheap portable thicknesser

Screwfix now stock lengths of timber.
38 x 63 x 2400 . Be more than enough support for a 5ft panel just offset noggin it for a little extra rigidity in the middle.
Think it’s around £3 a length