Glulam Purlins In Swimming Pool Trusses û Moisture Movement
Glulam Purlins In Swimming Pool Trusses û Moisture Movement
(OP)
I have a design carried out by another engineer which I need to finish off.
We have steel trusses spanning 25m over a swimming pool. The top truss cord is braced at 2m centres by glulam purlins (eventually back to a horizontal wind truss).
The wet environment is likely to cause the glulam to expand and the timber could split at the bolted connection to the truss.
I can’t uses slotted holes to allow for this movement as I will lose my lateral restraint to the top cord of the steel trusses.
Has anyone come across this before? Am I unduly worrying about dimensional changes in the timber?
We have steel trusses spanning 25m over a swimming pool. The top truss cord is braced at 2m centres by glulam purlins (eventually back to a horizontal wind truss).
The wet environment is likely to cause the glulam to expand and the timber could split at the bolted connection to the truss.
I can’t uses slotted holes to allow for this movement as I will lose my lateral restraint to the top cord of the steel trusses.
Has anyone come across this before? Am I unduly worrying about dimensional changes in the timber?






RE: Glulam Purlins In Swimming Pool Trusses û Moisture Movement
The issue with pools is adequate air infiltration management the location of the vapor barrier and proper HVAC design.
The Architect must be dogmatic about air and vapor barrier location and detailing. the Air barrier has to almost be perfect and the HVAC has to control the RH and keep the space under slight negative presure or there will be condensation problems. That's what will destroy your glulams and any other wood.
pools = lots of lawsuits. Be careful.
Tim
TAM Consultants
RE: Glulam Purlins In Swimming Pool Trusses û Moisture Movement
Just put the bolts on hand tight in slotted holes, and tighten them down a month or so after the pool is filled with water and the building heated. Most of any initial expansion will take place during this timeframe. Make sure you spec this too.
You know, too, putting a vapor barrier paint over the glulams, assuming they are fully cured, would help with any moisture problem too.
Mike McCann
MMC Engineering
RE: Glulam Purlins In Swimming Pool Trusses û Moisture Movement
RE: Glulam Purlins In Swimming Pool Trusses û Moisture Movement
Many thanks all