On Saturday, 12 May 2018 15:51:54 UTC+1, John Rumm wrote:
On 09/05/2018 10:56, Tim Lamb wrote:
In message , John
Rumm writes
On 07/05/2018 23:28, Tricky Dicky wrote:

Expansion is minimal along the grain. However its going to be hard
to make any sensible estimate unless you know the water content
when it was installed.

Also kiln dried lumber tends to exhibit less seasonal change than
air dried wood.

What is currently supporting it?

The beam is a section of pressure treated decking joist which along
with all the rest of their timber products was stored in open sheds
at the supplier. It is supported on two gate posts one affixed to the
garage the other about to be attached to the house wall held in place
in rebates by coach bolts.

In the circumstances it seems unlikely it will expand much. Personally
I would just trim a couple of mm of the length to create a bit of
expansion room, and allow the ends to dry out should they get wet.
My local experience of Builders Merchants storage is that treated timber
is stored unprotected from weather/Sun etc:-(

Indeed, so if its staying outside, conditions will likely continue to be
similar.

resulting in noticeable sideways seasonal expansion but no noticeable lengthwise expansion, as said a while back.


NT