Movement Joints

[LA3222]

Are these required in the blockwork skin wrapping my TF? The architect never mentioned them, the brickies haven't so I assume that the answer is no however this is a prime example of something that I catch a sniff off that then keeps niggling away in my mind until I can find a definitive answer - haven't found one yet so I hope someone here knows?‍♂️

[Russell griffiths]

How long a run?

used to a lot in thermalites but don’t see it practised as much in aglights 

used to be about every 6m but I’m very out of touch with today’s chuck it up methods. 

[MikeGrahamT21]

Spot on @Russell griffiths every 6m

[LA3222]

@Russell griffiths my longest wall is 14.5m, there are eight openings in that wall for windows/doors. No mention on architects stuff about expansion gaps and BC haven't made any comment either! We are using 7N medium density blocks.

[Oz07]

I think masonry now on 12m before gap needed Google it. 

I've got a wall just under 12m and I've put one in the middle. They don't cost much to put in so just do it for piece of mind. You need the slip ties with the condoms

[Brickie]

What’s the finish?

[LA3222]

@Oz07 I have been googling extensively and nothing seems to be explicitly black and white.

 

@Brickie The finish is silicone render.

 

 

My front/rear walls are 14.5m and the sides are 8.4m.  After a lot of googling and trying to get an answer out of BC/Render Supplier/Architect I have told the brickies to put one in the middle of the rear wall and two in the front.

 

The reasons for one then two are they split the wall conveniently in line with where down pipes will be so can be hidden easily enough.  I have made this decision using the following information:

 

Concrete Block Association (https://www.cba-blocks.org.uk/wp-content/uploads/2018/03/CBA-4pp-Movement-control-datasheet-rnd2.pdf)

 

TYPICAL SPACING OF MOVEMENT JOINTS

Un-reinforced blockwork 9m

 

NHBC Technical Guidance Movement Joints in Masonry Walls (http://www.nhbc.co.uk/Builders/ProductsandServices/TechZone/NHBCStandards/TechnicalGuidanceDocuments/61/filedownload,65370,en.pdf)

 

Dense concrete block and brick (using dense aggregate gross density exceeding 1,500kg/m3) - 7.5-9m 

 

 

The only niggle with my plan is that the blocks I am using are 1450kg/m3 so just below the 1500kg/m3 that NHBC state, but I think that they are close enough - that's only 3% so this is the plan.

[Russell griffiths]

You normally get cracking at a window, I would run them up the sides of there if convenient. 

[Oz07]

I think better behind a downpipe else you have to start bedding lintel on dpc. Yeh think bricks are around 12m blockwork less like you say. Think you've done right thing 

[Russell griffiths]

32 minutes ago, Oz07 said:

I think better behind a downpipe else you have to start bedding lintel on dpc. Yeh think bricks are around 12m blockwork less like you say. Think you've done right thing 

Hadn’t thought of lintels ??

[Brickie]

Down pipes is best place for them. ? 

TBH,as the Brickie,sometimes they can work in your favour. You whack a profile up at the movement joint,bed the rubber part of the slip tie system in & run that section in before moving along & repeating. 

[epsilonGreedy]

Does a south facing wall need an expansion joint more than north facing one?

[Oz07]

I don't think you do it by elevation. I've seen a north facing wall in 60s bungalow which has a thermal expansion crack thru a window.