Building on top of flitch beam

[glassfan]

Hello, new to this forum, not great with technical terms but here goes ....

Am building extension with 5metre opening (for bifold glass doors). Structural engineer designed flitch beam to span opening and support flat roof.

Beam is now in place and need to put 2 courses of concrete block on top. Do I need to put something between the timber and the mortar, as am worried about the expansion of timber vs that of the masonry? (Timber specified was C24 grade and treated).

A friend suggested hardibacker board, but won't that risk crushing with the weight of the roof?

Can anyone help?
Thanks in advance.

 

[^woody^]

You should not be putting masonry on top of timber, and your SE should have told you this as part of his design

You probably need studwork or posts

 

[glassfan]

Thank you for your reply.

Could you explain studwork and posts, please, and how they will take the weight of the roof?

Don't know why the SE didn't say anything about that - he said that he had allowed for a couple of courses in his load calculations??

Thanks

 

[theoldun]

At times you can be to overcautious.
Present day practice frowns on wet building on timber, but I can remember back in 52 up until about 65 we used to brick over the top of timber bressummers, laminated ply beams and timber lintels day in and day out, and have never seen any fail.
Yes, you can have shrinkage. In a 225mm deep beam, possibly 3 to 9mm across the face grain, but providing enough weight on top, nothing is going to go anywhere.
To help her out, try and keep beam in house for couple of weeks with heating on before placing. Nail length of Exmet to beam and keep tight bed under first courses of block. Put length of Exmet in next course as well. Your SE has said he has allowed for couple of course of block, so he is not unduly bothered.
oldun

 

[^woody^]

If this beam is going above an extension door opening, then is it on an external wall? In which case it will be susceptible to different seasonal movement to any masonry above it.

I can't think of good reason why anyone would want to put masonry on top of a timber beam instead of more timber

If you google " timber stud wall " or " structural stud wall " and look at the images, then you will get the drift of how this will support the roof above

 

[chappers]

have to agree with woody, dont really think a flitch was the best solution for the job here

 

[theoldun]

I can't think of good reason why anyone would want to put masonry on top of a timber beam instead of more timber

Nor can I really, but as I have not seen drawings nor do I know what SE had in mind, would not be fair of me to comment or criticise.

don't really think a flitch was the best solution for the job here

Take it you have seen the drawings then.