Advice on DIY GluLam Car Port

[FozzieBear]

I have been quoted nearly £10k for a 2 bay oak frame car port. This is just the oak frame delivered to site with no roof timber or construction. I am sure I can build it much cheaper using C16 or C24 tanalised timber.
The car port is going to be approx 6.1m wide by 5.4m deep and supported on a dwarf brick wall on two sides and staddle stones at the front. 150 x 150 C24 beams are quite expensive but 200 x 47 are relatively cheap. I was therefore considering making the beam and post out of a DIY Glulam construction using three 200 x 47 C24 timbers glued and screwed together for the beams and 175 x 47 C16 for the posts. The front beams will only be 3m long but the front to back will be 5.5m long. however the only one not supported in the centre of its span is the middle one as the other will be infilled with 100 x 47 studding. I have attached a sketch of the proposed car port and another sketch of how the beams will rest and fix to the posts. I will put braces on all corners where the beams sit on the posts. the great thing about this method of construction is that I can fabricate the beams on my own in the barn and then get help to lift them into position. except for the rebates for the braces there are no mortises and tenons to cut as they are the thickness of the individual timber.

I am assuming I will need planning permission as its slightly over 30 sqm and only open one side unless they count the large openings at the back as being "open". My biggest concern though is if I have to submit for building regs and how I get a structural engineer to approve the load calcs on the beams. Can anyone see any pitfalls to my proposed construction design?
Fozzie

 

[stevie888]

You're not really making Glulams which are made up of thinish strips of wood stacked vertically with high strength strips on the outside, just tripling up standard timbers. All very simple stuff for an SE.

I think you'll need PP not because of the area but because its joined onto an existing and the whole structure is then assessed against the relevant criteria so >4m high will stop you

 

[FozzieBear]

You're not really making Glulams which are made up of thinish strips of wood stacked vertically with high strength strips on the outside, just tripling up standard timbers. All very simple stuff for an SE.

I think you'll need PP not because of the area but because its joined onto an existing and the whole structure is then assessed against the relevant criteria so >4m high will stop you

Thanks @stevie888 No appreciate they are not proper GluLam but couldn't think of another way to describe the fabrication. I just need to find a local structural engineer to look at the approach in principle before giving actual dimensions.

 

[freddiemercurystwin]

More like flitch beams and they'd be bolted together rather than glued.

 

[FozzieBear]

More like flitch beams and they'd be bolted together rather than glued.

Thanks @freddiemercurystwin. I read somewhere that to distribute the load across all three timbers they had to be glued with construction glue as well as screwed/bolted.

 

[freddiemercurystwin]

Glulams are fundamentally different to what you're proposing, they're formed with thin strips of timber bonded together under high pressures. You cannot replicate that process in a domestic setting.