Hello!
We are working on creating an opening in one of the load-bearing walls in our 1.5-story house with dormer windows. The wall is a wooden construction with a wooden beam on studs.
We want to create a 3-meter opening and use a glulam beam to support it.
We talked to a designer at a building supplies store in Kumla who did an estimate using some program where she input parameters like the type of house and what the roof was made of. She determined that we should use a glulam beam that was 115mm wide and 360mm high.
I have a question: Instead of calculating using a bunch of standard parameters, couldn't one calculate what the current construction is built to support, and based on those figures determine which dimension of glulam beam can replace the load. According to the principle, if we build as strong as it is today or stronger, it should be sufficient.
Does that sound reasonable? The current construction consists of studs with 600 mm spacing, and the beam they support is 75x75mm. The studs themselves have an old measurement of 75x55mm (the house is from 1959).
Grateful for comments!
Cheers
- Björn
We are working on creating an opening in one of the load-bearing walls in our 1.5-story house with dormer windows. The wall is a wooden construction with a wooden beam on studs.
We want to create a 3-meter opening and use a glulam beam to support it.
We talked to a designer at a building supplies store in Kumla who did an estimate using some program where she input parameters like the type of house and what the roof was made of. She determined that we should use a glulam beam that was 115mm wide and 360mm high.
I have a question: Instead of calculating using a bunch of standard parameters, couldn't one calculate what the current construction is built to support, and based on those figures determine which dimension of glulam beam can replace the load. According to the principle, if we build as strong as it is today or stronger, it should be sufficient.
Does that sound reasonable? The current construction consists of studs with 600 mm spacing, and the beam they support is 75x75mm. The studs themselves have an old measurement of 75x55mm (the house is from 1959).
Grateful for comments!
Cheers
- Björn
In general, when it comes to sizing for residential buildings, the limits are not whether it will hold or not. Instead, there is a maximum allowable deflection, and then it must take much more load before it breaks straight off.
But it is possible to visit a roof truss supplier/designer with your existing drawings to get a more precise calculation of what you need.
But it is possible to visit a roof truss supplier/designer with your existing drawings to get a more precise calculation of what you need.
You've had a calculation done, it should certainly work well. I've done a similar job in a former exterior wall here at home. There is a thread somewhere about this but here are some pictures:
http://www.mugglo.net/byggteknik/balk/
http://www.mugglo.net/byggteknik/balk/
Personally, I think steel is very nice to work with. I have installed two steel beams and a wooden beam in the house in connection with the new floor plan on the ground floor.
The reason I chose steel was precisely to reduce the dimension and weight a bit. Unfortunately, I haven't been able to find any calculation tool (cheat sheet) for steel on the web, so I used a tool from a glue-lam manufacturer online to get a reference for the loads. Thereafter, I sized the steel beam myself according to the load case that the web tool presented for my type of house.
To get a more accurate calculation in your case, just consult a structural engineer who can do the calculation and choose a suitable beam for you. I assume you also need to submit a building notification. Also, consider how you will get the beam into the house.
The reason I chose steel was precisely to reduce the dimension and weight a bit. Unfortunately, I haven't been able to find any calculation tool (cheat sheet) for steel on the web, so I used a tool from a glue-lam manufacturer online to get a reference for the loads. Thereafter, I sized the steel beam myself according to the load case that the web tool presented for my type of house.
To get a more accurate calculation in your case, just consult a structural engineer who can do the calculation and choose a suitable beam for you. I assume you also need to submit a building notification. Also, consider how you will get the beam into the house.
Since TS has not specified the span of the house, it is probably risky to recommend a more slender beam than the one he initially received?
JOW: Aha, I understand! That explains why you overestimate a bit more than needed.
Can one say that if you had an infinitely rigid beam, which remained completely rigid up to the breaking point, you could think as I said?
Thanks for your responses, by the way, your opinions and experiences are very valuable to me.
We'll go with the beam we've been recommended in glulam. The first thought was to use steel to reduce the dimensions a bit, but our supplier delayed, and we're short on time.
- Björn
Can one say that if you had an infinitely rigid beam, which remained completely rigid up to the breaking point, you could think as I said?
Thanks for your responses, by the way, your opinions and experiences are very valuable to me.
We'll go with the beam we've been recommended in glulam. The first thought was to use steel to reduce the dimensions a bit, but our supplier delayed, and we're short on time.
- Björn
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