Can I cut a joist end like this?

mhuk · 20 Mar 2008

To fit an 8x2 joist in my loft, I would have to cut the end of the joist, removing a piece about 5 x 10" to enable it to fit next to the existing ceiling joist and under the beam under the rafters (is it called a pole plate?):

(click image for a bigger version).

The joist will supported at the other end by a load bearing wall and joined to another 8x2 joist going the other way (as shown in my other thread). I may add noggins as well for additional strength.

Will cutting the joist in this way still meet BR?

Thanks

noseall · 20 Mar 2008

you seem to have an unusual arrangement whereby the wall plate is sitting on top of the ceiling joists. uncommon, but not unheard of.

also, it seems as though there would be little bearing should you wish to sit the new joists on top of this wall plate. plus the fact there is a void beneath the intended bearing location.

i think you should fill the gap beneath the existing plate with bedded masonry and sit another plate in front of the existing. then sit the joists on top of this double width plate.

the joist cut will need to slope with the rafters.

mhuk · 20 Mar 2008

Cheers for your reply and suggestion. A quick look in my 1960 edition of "Building Construction" it's not a wall plate, it's a pole plate; the dictionary says:

a horizontal timber resting on the tiebeams of a roof and receiving the ends of the rafters. It differs from the plate in not resting on the wall.

The ends of the ceiling joists rest of pad stones and have about 6" of support (the external wall). There is also the top of the inner coarse of the external wall on the "inside" of the pad stone that do not support the ceiling joist.

This picture (although it doesn't show any ceiling joists) shows the position of the pole plates:

timbers in a roof: a, wall plate; b, tie beam; c, king post; d, strut; e, principal rafter; f, pole plate; g, purlin; h, ridgeboard

Given that end of the 8x2 would be resting on a pad stone, can it be cut as described and retain it's strength/ meet BR?

edit: just been in the loft and there is 12" of bearing at the end of the ceiling joist.

Deluks · 20 Mar 2008

We have the same, was a usual practice many years ago, as it makes for a more rigid roof structure. But you don't see it done these days, mainly due to the cost of the extra timber and the usage of modern timber connectors and other metalwork.
My guess is that you could cut through it, the cut being the same thickness as the joist you are inserting and then fix it back to the new joist using a metal right angle bracket on each side, to maintain the integrity. I don't see it going anywhere as this 'pole plate' (never heard of that before) is the braces in a belt 'n' braces roof construction.

Shytalkz · 21 Mar 2008

It's not that unusual a detail. It was done to keep the eaves overhang and dentil detail higher than would have been the case with a wallplate-under-the-joist detail.

Cut through it and strap the cut ends back onto the new joist with twisted BAT straps. Obviously you need to chamfer the joist end to suit the roof line.

mhuk · 21 Mar 2008

Many thanks for the reply. I'm having problems visualising how to use a twisted strap.

I cut a 2" slice out of the pole plate. Insert chamfered 8x2 into gap/ on top of pad stone and adjacent to the existing ceiling joist

Where does the strap go? Do you mean one "side" of the strap attaches to the front of the "front" of the pole plate (as you look at it) and the "side" of the twisted strap attaches to the side of the new joist,as below (although the contact area will only be a few inches on the pole plate):

And can I use these connectors between a noggin and a joist:

or just nail them?

Sorry for being a bit slow- need some more coffee

Shytalkz · 21 Mar 2008

mhuk said:

Use this but rotate it through 90 degrees: short bit goes on pole plate, long bit goes on side of joist. Nails are fine, nothing more exotic than that is required

mhuk · 21 Mar 2008

Excellent

That's what I thought (couldn't find a picture with the strap the other way around). Thanks for your help again.

Guess you mean 180 degrees

Shytalkz · 21 Mar 2008

Well, if we're going to be pedantic

it's actually 90 degrees counterclockwise (with the eaves to your left) from as shown, about its vertical axis and then 90 degrees clockwise (looking towards the eaves) about its horizontal axis

Deluks · 22 Mar 2008

mhuk said:
And can I use these connectors between a noggin and a joist:

Noggins and joists are at right angles to one another, these connectors are for timbers that are joined together that are running in the same direction, and used with a bolt through both members.

Nailing will be fine, or use mini-speedy hangers if you're lazy/fussy.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Can I cut a joist end like this?

Similar threads