Lintel Sizes

Ok,
I'm new to the game. Maybe my search skills are poor too! i've been searching around for the past day looking for information about lintels.

I am in the process of renovating my home (extension by a couple of rooms and En-suite).
The home is fairly old. I'm replacing the old rafted roof with a Truss roof which has just been completed by a company.

Whilst waiting for the truss roof we removed old windows from the existing home in preparation for new windows. The issue i have is that the Lintels and existing wall frames (hardwood) are fairly old and i'm a bit worried about the truss & point loads. The truss company has given me information of were to put extra studs to support the truss roof which was good. The issue is now with the lintels.

For example, we are placing a new stacker door where a window used to be. The dimesion of the wall is 7130 wide. The stacker door opening is 3650 wide. Only jack trusses sit over this opening.
I have spoken to a carpenter who told me that we require a 290 x 90 lintel above this opening. Preferably MGP12. Is this correct? Will the MGP12 suffice or do we need F17?

Now, i don't want to bore you with other questions about other window openings so I was wondering if there was a book/web page/files etc etc that list the recommended lintels for different openings.

Also, 1 final question - does it matter if the lintels are placed directly under the top plate (supported by noggins) or above the window opening (noggins to top plate)?


Thanks in advance
K

You can find span tables for lintels under 'Wall Framing' here:
http://www.fordtimbers.com.au/dpr_span_tables.htm
They only go up to a 2400 opening though.

For bigger openings, there are tables for LVL Hyspan here:
http://www.chhfuturebuild.com/WSMApa...-46673,00.html

Quote:

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Originally Posted by karthioli

Also, 1 final question - does it matter if the lintels are placed directly under the top plate (supported by noggins) or above the window opening (noggins to top plate)?

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It doesn't matter.

thanks for the info

Also the truss company would be able to help you with that info.

http://www.hyne.com.au/pagefiles/dihv5program.htm

is my favourite - gives you both lgl and MGP12 sizings if you want. go lgl though - lighter and straighter (and cheaper) than normal timber.

I priced some Hyne beams about five years ago that were specified as floor joists by an engineer. They were a lot dearer than LVLs, so I convinced him to change the spec.
I don't know what their pricing is like today though.

Quote:

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Originally Posted by toecutter

Also the truss company would be able to help you with that info.

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i wish. they have been totally and utterly useless.

speaking of trusses, The extension were the truss company (or should i say pre-fab) created new internal walls there is a 20mm allowance for the deflection of the trusses.
now the truss company tells me that the defelection wont be more than 20 mm. They installed these trusses on the existing top plate (did not put a second one down) and as a result the trusses are basically sitting 2-5mm from bottom cord of trusses to the top plate of the 'existing internal' walls. Now if the trusses are to deflect 20mm then i have an issue as they will sit on the 'existing internal' walls.

Now the truss company has said that the best thing 'for me' to do is to cut the studs of the existing walls down 20mm (to match the height of the new internal walls they provided). Is this valid?
Also, the current top plate on these existing internal walls in 50mm. If i replace the 50mm with a 35mm top plate is that ok (i.e. standards etc etc)?
It just seems an easier solution then shortening all the studs by 20mm.

Now my frustrations are that i've spoken to a few people. Tradies and engineers and they've all said that a second top plate should of been put on before the trusses!!!!

Sorry a bit off this topic track but just had to let this out!

Cant you just get a recipricating saw and cut out the existing top plate sections under the truss and block underneath the cut of section of top plate. I would imagine you would have much of a frame left after shortening all the studs.

Quote:

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Originally Posted by thebuildingsurv

Cant you just get a recipricating saw and cut out the existing top plate sections under the truss and block underneath the cut of section of top plate. I would imagine you would have much of a frame left after shortening all the studs.

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so you are saying to basically put noggins between the studs underneath the top plate that will be removed?

Quote:

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Originally Posted by thebuildingsurv

Cant you just get a recipricating saw and cut out the existing top plate sections under the truss and block underneath the cut of section of top plate. I would imagine you would have much of a frame left after shortening all the studs.

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Yes, as long as it isnt a bracing/loadbearing wall.

Are you haveing a inspection of this new work karthioli?

house used to be a rafted roof. had a look under these walls and concrete stumps are about 1m apart (on average).

trusses were designed to clear span i was told.

and yes inspection to come but engineer booked in.

Quote:

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Originally Posted by karthioli

house used to be a rafted roof. had a look under these walls and concrete stumps are about 1m apart (on average).

trusses were designed to clear span i was told.

and yes inspection to come but engineer booked in.

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Your internal walls can be made out of paper as long as it isnt a bracing/loadbearing wall.

Leave the top plate there and just cut out where the truss would hit it in full deflection. Block first so the frame doesnt fall apart. I wouldn't really matter if it was a bracing wall if it is done this way.

but what if the internal wall is running underneath the span of the truss?
and What if the truss deflects 20mm and eventually sits on this wall.

so is there a minimum size for the internal wall top plate?

appreciate the suggestions btw.

if it sits directly paralell under the truss then the only way i can see to do is shorten the studs like truss company said. One way to do this is fix a peice of timber along the side at the top of the existing studs (to keep them together) and cut away, then install the new top plate. Top plate should be 35mm min. Or it may be quicker to build a new wall.

If its not a bracing/loadbearing wall and paralell under the truss id do as thebuildingsurv recommends.

Nail a piece of timber to the side of the frame.
Set the piece at the correct hieght to suit your power saw and use it as a guide then cut the studs down and fix a piece of 35mm as a new top plate.

thanks. nice idea. i'm going to assume that it will be loadbearing just in case the trusses do end up sitting on the wall - i know it wont but i'm paranoid now!

i'm starting to lean towards the new wall idea !

If the trusses sit on a wall that they where not designed to it could cause major structural issues.

well i was told that the trusses have been designed to clear span. but get what you are saying.

http://img147.imageshack.us/img147/3946/trusszi4.jpg

diagram???

which tool is best to use. reciprocating saw or is the power saw ?

A power saw would get the cuts more square, but you'd have to remove the top plate and all the nails first if you value your blade. A recipro with a metal cutting blade would slice through everything with the top plate in place, but they can wander out of square.

Quote:

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Originally Posted by karthioli

diagram???

which tool is best to use. reciprocating saw or is the power saw ?

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Thats what could happin to your truss top chord if it sits on a internal wall:o

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Originally Posted by toecutter

Thats what could happin to your truss top chord if it sits on a internal wall:o

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Definately. Unless there is a joint (webs intersecting within 100mm).

Even then it could change the whole dynamic of the roof trusses.

But have they cambered the trusses up? And if it is only clearing the internal wall by 5mm then it must be fixed by dropping down the internal non loadbearing walls. I can't believe that they were that stupid to allow the loadbearing walls to be at the same level.

Ideally, the trusses should sit flat after 6 months of loading, so if they are not cambered either they are lightly loaded and will only deflect 1 or 2mm or the company has made a mistake.

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Originally Posted by DvdHntr

I can't believe that they were that stupid to allow the loadbearing walls to be at the same level.

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Yeh, from my experience internal wall frames are designed with minimum 20mm clearance, and special brackets are supplied for connection to give the internal walls more lateral stability, whilst still enabling vertical settlement of the truss bottom chord via the slotted nailing points, which are supposed to be nailed at the top of the slots.
It would certainly cause some havoc with your cornices if there was 20mm movement though. What is the recommended time period between roof loading and plastering anyone?

Quote:

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Originally Posted by pawnhead

Yeh, from my experience internal wall frames are designed with minimum 20mm clearance, and special brackets are supplied for connection to give the internal walls more lateral stability, whilst still enabling vertical settlement of the truss bottom chord via the slotted nailing points, which are supposed to be nailed at the top of the slots.
It would certainly cause some havoc with your cornices if there was 20mm movement though. What is the recommended time period between roof loading and plastering anyone?

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Special Brackets are called "internal wall brackets. They only support the wall laterally and so the wall doesn't get loaded by the roof.

In most cases, the truss will have less than 5-10mm of movement left after initial loading. Usually the plastering is a week or two after the roof and walls are all up. And even then, the cornice is usually the last thing installed for this reason.