1930 Archaic Roof System - timber lattice barrel type roof over a gym

[frogit22]

I have come across an archaic building system on a project I am working on. It can be best described as a lattice typ system. The building was built in 1930 and the roof is clear spanning a gymnasium (68 feet). I have removed only a small portion of the finish to discover a network of approximately 9" deep wood timbers that I can only describe as a lattice. The wood members are not orthagonal to the span of the roof - more like a 45 degree angle. Different pieces frame into each other.

About every 16 feet there is a 2" diameter tie rod that spans the gymnasium - I'm thinking its a retro-fit but don't know for sure.

Does anyone have an old book that shows a system similar to this description? Sorry I don't have a photo.

 

[InDepth]

Can you upload a sketch. You could try searching the Google Book database for online versions of older books.

 

[ARKeng]

Unfortunately no help. I've seen that before though -- the building I took the California PE exam in in Pomona had that for a roof and was baffled.

 

[frogit22]

see attached quick hand sketch.

 

[oldrunner]

I'm not too sure from reviewing your sketch, but this may be a lamella roof that was used on many of the Purity Grocery stores in California. The design is mention is some of the older AITC timber design manuals, but I'm not at my office at this time to check. I believe the roof at the Jaguar dealership in old Burlingame has this kind of a roof.

 

[msquared48]

From your sketch I do not think it retro, but a tension tie rod to take the thrust from the arch.

Mike McCann
MMC Engineering

 

[jike]

This is a lamella roof. One advantage of this type of construction was the long spans with relatively short members.

 

[oldrunner]

Check pages 4-67 through 4-75 of the 1966 edition of the Timber Construction Manual of the AITC.

"The Lamella roof is a curved roof framed by a system of intersecting skewed arches made up of relatively short members call lamellas. The lamellas are bolted together at an angle, so that each is intersected by two adjacent lamellas at its midpoint to form a series of interlocking diamond shapes."

You sketch didn't exactly look like this

 

[frogit22]

It looks similar to this attached photo, but built in 1930.

It has a span of 68 feet, but the arch is fairly flat - I figured the radius of the roof arch was around 55 feet. The building is located in Eastern Connecticut.

 

[frogit22]

I think lamella roof is it, I don't think I have that reference and I have searched all the antiquated structure systems in my reference library. Can anyone help ? Much appreciated.

 

[jike]

There were 4 different types of lamellas according to Wikipedia.

 

[PST09]

There is a book called 'Modern Timber Engineering' which includes some refrences to the Lamella Roof structure.

http://books.google.co.uk/books?id=...oof&dq=lamella+roof&ei=9XZkSrSZNpTklATC-_3BDg

Unforfunatly i dont have a copy hanging around but someone else might.

If your building was built in 1930 there is every possibility that the structure is of this type, as Lamella roofs were introduced into the US in around 1925...

 

[InDepth]

Call the American Wood Council (AWC) they have a historical library of references and may be able to fax you items/excerpts and/or identify the system.

http://www.awc.org/AWC/about.html

Phones General (202) 463 2766
Helpdesk (202) 463 4713
Publications (800) 890 7732
(608) 232 9354

Fax (202) 463 2791

 

[frogit22]

I just spoke to AITC publications department - who is supposed to be sending me some info on lamella roof system. I will let you know how it looks and/or post it.

thanks.