Building regs and home milled timber

[billpierce]

Doing an extension. Would like to use some larch or oak as structural timbers. Anyone know the craic with stuff I have milled or using a small local saw mill? The builder was a bit unsure, I'm pretty sure it's possible just hoped someone could point me in the right direction? Ta

[LeeGray]

You can use it definitely. I used a structural engineer to get through building regs on ungraded timber, he’ll do a visual inspection on a good sample of the timbers to sign off. He’s local so could pass his details on if you like but he may be too pricey if it’s just a few choice timbers your builder wants to use for the aesthetic value.

[billpierce]

Yes please send details. I can atleast have a chat with him about it. It'll be for 2 or 3 a framed and some decent beams above door openings etc.

[LeeGray]

Pm sent

[Squaredy]

1 hour ago, billpierce said:

 

Doing an extension. Would like to use some larch or oak as structural timbers. Anyone know the craic with stuff I have milled or using a small local saw mill? The builder was a bit unsure, I'm pretty sure it's possible just hoped someone could point me in the right direction? Ta

 

Yeah we did this two years ago - ungraded and unseasoned Larch.  Our builder seemed to think it would be fine even though it was a slight variation from what the drawings specified as these said it had to be treated softwood.  The building control guy seemed happy and signed it all off.  No-one with any formal qualification certified or graded the beams.

[billpierce]

12 hours ago, Squaredy said:

Yeah we did this two years ago - ungraded and unseasoned Larch.  Our builder seemed to think it would be fine even though it was a slight variation from what the drawings specified as these said it had to be treated softwood.  The building control guy seemed happy and signed it all off.  No-one with any formal qualification certified or graded the beams.

Sounds unusually straight forward

[Woodworks]

I know when we built our place I used some larch that was supposed to be graded but came with no marking for C16. I had to pester to get some certification that frankly looked pretty dubious when it arrived. When building control came for sign off the BC said he was qualified to grade timber. Now I dont know how many are qualified in grading but some clearly are.

[Macpherson]

There was a self build featured on telly where Larch was used from the builders own wood, it was taken to a mill who sawed it and then graded it......the guy was sweating blood about whether it would make the grade....in the end it exceeded C50 !

 

In my experience Larch is massively tougher than any of the usual white softwood available from builders merchants and can be [ at least from the point of view of a builder ] self certified in a similar way to oak for example, ie, simply inspect for obvious defects.....whether this stands up to regulations, I don't know,   cheers.

[ucoulddoit]

I googled visual grading of timber and found the following link which might be of use: http://whitewoodmanagement.co.uk/wp-content/uploads/2014/08/Guidelines-for-selecting-and-processing-timber-for-visual-stress-grading-for-structural-use.pdf

What form of construction is the extension and was a structural engineer involved with the original design? I’m a structural engineer and am happy to pass on the following. If you’re hoping to use self milled larch or oak instead of C16 softwood from a builders merchant for the studs and framing in a timber frame panel with sheathing I wouldn’t be too concerned, provided obvious defects were avoided such as large knots, etc. The link above has a list of defects to look out for. If it’s a frame with traditional pegged mortice and tenon joints, the timbers will probably be more highly stressed, so I’d want individual timbers to be checked more thoroughly. You would need to visually grade each individual piece of milled timber. Looking at a small sample would give an indication of the grade/strength that might be achieved. But it is the size and type of defects (or lack of them) in each piece of milled timber that determines whether it achieves a specific strength grade. At the end of the day, if the extension needs to be inspected/approved, it would be advisable to discuss this proposal with the inspector to find out what procedures he would need to be followed. But using self milled timber for structural use is certainly feasible.

Andrew

[billpierce]

Thanks for the help peoples! I'll speak to building inspector see what he says.