Beam construction

[mlbillow]

I need to join two 2x10x10 cedar boards to create a 20' beam. I am building a pergola and am trying to avoid having a beam in the middle. What is the best way to join these two boards together? They wiill be supporting 2x6's (spaced at 12 or 16 inch center) and 2x2's (spaced on 4 inch center). Any help would be greatly appreciated.

I also attached a picture of what the finished product will look like, execpt the closest set of beams (2, 1 on each side of the 6x6) will be 20' while the ones closest to the house will be 16'.

 

[mlbillow]

Ok, I figured it out.....My father calls is a Z joint, but really it is a form of scarf joint.

I was surprised, it is a very strong joint! I made a couple of practice ones out of some scrap wood as you have to be pretty precise for a nice tight fit. I didn't even glue it and it was almost as strong as the original board. My father has used this to make some really long beams (35').

 

[masona]

You could use something like 4 treaded stud bolts into the timber mixed with chemical resin to bond it. Use a long drill bit and a extension bar to extend the hole if needed

 

[JohnD]

I didn't understand that. For my info, what size is "2x10x10?" is it inches?

And are you joining them end-to-end into a single long beam with no leg under the middle?

 

[masona]

I didn't understand that. For my info, what size is "2x10x10?" is it inches?

And are you joining them end-to-end into a single long beam with no leg under the middle?

I'm guessing 2 x 10' beam butted together making 20' beam

 

[JohnD]

And you can really join them end-to-end like that? I'm very impressed, have been thinking about a 5-metre long carport but worried about banging the car or doors into the legs.

 

[joe-90]

No timber will join end to end like that. I would use 1" timbers with joints as far away from each other as possible (One in the middle of one piece and two either side in the other piece). Then glue them all together and also bolt them.

joe

 

[Scrit]

Hi ML

The normal length of the scarf joint is supposed to be 2.5 to 3 times the height of the timber, so for 10inches you need a joint which is 25 to 30inches long. The joint can be even stronger if you put a pair of cross wedges into the middle of the joint to push the bird's tongues into their housings, as here:

I have to say that there are many more practitioners in the USA these days due to the much higher preponderance of timber-framed houses you have over there. Reckon if they're strong enough to build houses they'll be strong enough for your gazebo thingy! Good luck!

No timber will join end to end like that. I would use 1" timbers with joints as far away from each other as possible (One in the middle of one piece and two either side in the other piece). Then glue them all together and also bolt them.

Another stunning master statement, joe. Yet again we joiners and carpenters of the world stand in awe of your superior knowledge We are not worthy You really need to go and teach all those misguided timber frame builders in the USA the right way to do things with a joe-90 wooden poultice.

Scrit

 

[Thermo]

Another stunning master statement, joe. Yet again we joiners and carpenters of the world stand in awe of your superior knowledge We are not worthy You really need to go and teach all those misguided timber frame builders in the USA the right way to do things with a joe-90 wooden poultice

Scrit
That will be the joint weve been using in this country for a few hundred years for large timber frame buildings as well then. Perhaps Joe-90 might like to pay a visit to the weald and downland museum where they have a large collection of old timber buildings that have been moved there and have a look at some of the joins they have used there on the framing and tell them it cant be done as well while you are there.

 

[joe-90]

Quicker, easier and stronger to use a composite construction. Come on fellas - join the new century.



joe

 

[Scrit]

That will be the joint weve been using in this country for a few hundred years for large timber frame buildings as well then.

Yes, misguided though we are, I think it is. Isn't it a shame that for centuries we miserable woodworkers have been going along trying to make strong, neat, durable joints which don't require any glue at all when we should have been using Joe-90's Patent Wood Poultice (TM). It's enough to make one weep.

Quicker, easier and stronger to use a composite construction. Come on fellas - join the new century.

I'm sure that Joe will humiliate us all even further by quoting the relative strength of his fabulous Joe-90's Patent Wood Poultice (TM) as opposed to the pitiful old-fashioned wedged scarf joint I was so wrongly taught at college. Well, Joe, quote me the figures. The scarf joint properly done retains between 70% and 90% of the beam strength and rigidity of a single wood beam - without any glue at all. How does your stupendous Joe-90 Patent Wood Poultice (TM) compare?

Scrit

PS Joe-90's Patent Wood Poultice (TM) is called a lap joint

 

[masona]

And you can really join them end-to-end like that? I'm very impressed, have been thinking about a 5-metre long carport but worried about banging the car or doors into the legs.

You can BUT providing it need no weight to support above such as a pregola. I would say the best easiest way is to up to 1m half-lap joints with glue + bolts + square washers + timber connector (bulldog type)

John, have you seen these type of roof without supports, not cheap though.

 

[JohnD]

seen it, but didn't like the look of it. I'm not a skilled woodworker, so perhaps I'll use the bolts and poultice method (!)

 

[Scrit]

John

I'm sure you could manage a long halving joint with some through screws and a bit of glue (polyurethane if you need the gap filling or exterior grade PVA). Strong enough, no bolts and no poultice.

Scrit