Which joist hanger & span help

13 Mar 2011
Reaction score
United Kingdom
I have been laying new joists in my attic, they're 195 by 75mm x 4.3m finished size

around the bay window I need to have a trimmer joist that spans around 2.5m then hang the ends of about 5 joists from it, the trimmer joist will be hung about 100mm from the ends of the joists supporting it

First of all will it be ok to use a piece of the 75x195 for the 2.5m trimmer joist? will this be adequate to support the ends of 5 other joists?

Will the 2 joists supporting the trimmer be adequate seeing as i'll only be hanging the trimmer 100mm from their ends?

finally what type of hanger do I use? a brickie friend mentioned something about a timber to timber hanger that is nailed vertically to the trimmer and has a bit that wraps over the top of the joist , I cannot find any of this type, they all seem to be for masonry to timber
Sponsored Links
I have an old book that says the rule of thumb for arriving at the extra dimensions required in the trimming joist [the two joists supporting the trimmer] is to add 1/8 inch in breadth to the size of the common joist for every trimmed joist supported by the trimmer. So you should use 195 x 90 (or wider I suppose). I would also make the trimmer this size.
Caveat: I am no expert so I am just quoting from a book, and anyway ideas can have changed since my antique reference was published.
I think a sketch of what you are talking about would help.. i've no clue..
Hi thanks for the replies

I'm going to double up the joists supporting the trimmer by coach bolting and glueing them together, I will also double up the trimmer joist , I think this will be more than adequate and won't add too much more cost to the job.
Sponsored Links
Doubling up the supporting joists is the recognised and recommended method and in fact i think Building Regs insist on it in most cases if not all.

DIYnot Local

Staff member

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