Review of Timber Strengths

I had a wander around the site today and checked out the types of timber used and the general spans etc.

It looks like a combination of MGP12 and MGP10 were used.  Also spans went from 1400 to 1650 for the bearers and the joists were typically spanning similar lengths with spacing of 450 consistent across everywhere.  The bearers were 2/95x35 sections and the joists were 95x45.

Unfortunately I could only access the code for F7 grade timber which has the following properties compared to MGP10

E = 7900 cf 10000
f'b = 18 cf 17

As deflection often governs span lengths in timber framed construction it is really only the ratio of the E values that matters.  Therefore I can just adjust the allowances for the F7 up to MGP10 based on the ratio of E values.

AS1684.2N1N2 F7 Supplement allows 1400mm spans for single spans and 1700 continuous spans for 450mm spaced joists supporting load bearing walls.  This was consistent with what was on site.

Similarly the bearers seemed to spaced adequately given a bit of an increase from what can be seen in the table below.  So all looks good.

It's funny using such prescriptive codes compared to what I normally use but everything is looking good.