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Re: Brick shelf angles

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While I cannot offer any thoughts on Canadian codes, I will comment on
what I recall from a US point of view.  I cannot recall any direct
provisions in the engineered masonry sections that place prescriptive
retrictions on vertical spacing of brick relief/shelf angles.  I have not
reviewed things too closely in a while, so there might be some changes in
newer codes.

>From past experience, the spacing is largely dictated by
architectural/aesthetic reasons in combination with the engineering
requirements.  The thing that typically gets in the way with going too far
is movement characteristics (i.e. expansion/shrinkage characteristics).
If memory serves me (it has been a while since my last masonry veneer
project), I have done stacked brick on the foundation for about 3 stories
then a relief/shelf angle that supported up to another 2 stories of brick
before the next relief/shelf angle.  The real limit is how big the
movement joint below the relief/shelf angle needs to be and how badly the
archtitect wants that joint to be obvious/not so obvious.  The practical
limit usually is about 2 to 3 stories of brick.  And the practical limit
for the amount of brick that you can design the angle to support is about
2 stories max.

But, otherwise, my experience is that the engineering principles along
with architectural/aesthetic reason are what you use to decide it...not a
presciptive code requirement.


Adrian, MI

On Tue, 16 Nov 2004, Kevin Below wrote:

> What is the maximum vertical spacing for brick veneer shelf angles ?
> The Canadian masonry code S304.1-94, Clause 16.9.4 for empirical design
> of brick veneers states 11 metres to the first shelf, then a maximum
> spacing of 3.6 metres.
> I would like to be able to use 2 story spacing above the 11 m if
> possible for a concrete-frame building, total of 5 stories of brick
> facing.  That would translate to a single shelf angle ( at level 4)
> instead of 2 (at levels 4 and 5).  And with the price of shelf angles -
> apparently 225 $ a metre, about 75 $ a foot, (does that sound right ? I
> am still not convinced, but that's what the construction manager says),
> it's worth doing the research.
> The Masonry Institute at HYPERLINK
> ""http:/
> /  says that
> the 3.6 metre (12') limit was intended for wood stud framing, I suppose
> to relieve the shrinkage problems of wood.  Concrete framing has some
> shrinkage problems too, but normally not as much as wood.
> Since the code requirement in Canada is for empirical design, are there
> any Canadian engineers out there with an opinion on whether this
> requirement is binding or not ?  If I do a rational analysis and show
> that the expected shrinkage over 2 stories can be taken up with a single
> shelf angle, I think that it would satisfy the code, since it would not
> be an empirical design, and so would not come under clause 16.
> I would ask my friendly building official, but we don't have them in
> Quebec.  So no-one is going to challenge my decision, but I would like
> to do the right thing anyway.  Some of professional ethics thing I
> suppose.
> Kevin Below, ing., Ph.D.
> 290, rue Seigneuriale
> Beauport, (Québec) G1C 3P8
> Tél. : (418) 660-6969 poste 272
> Fax : (418) 660-6463
> ---
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