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Installing a concrete lintel, reassurance please


8ball

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Hi guys I am installing a concrete lintel in a single skin block work load bearing wall and just wanted to run through with you guys how I am going about it just to make sure I'm on the right tracks, I have searched google for most of my info but every project is different so I thought I would run it through with the Buildhub crew.

 

1st off background details:

I have a house - pic below

34490_25094118_IMG_31_0000.thumb.jpg.1428eef55583c9966ff55f4fbc97407c.jpg

 

The footprint is width 7m x Depth 6.32m - see pic below

591ac6ae80d7d_groundfloor.JPG.549ea5920a15a1fc53998b81331a762a.JPG

 

The trusses run front to back of the house and there is a Block work central wall which runs the entire width and this is where I want to create a new door way - pics below

591ac722be133_groundfloorjoists.JPG.25fa46079f5f1a930a0e10f343bf8676.JPG20170516_095514.thumb.jpg.2f7a82dda67ea74e04d3fd3fdecfa0cb.jpg

 

Above the ground floor load bearing wall is another block work wall that kinda follows the same path and creates part of the 1st floor rooms and above this of course is the roof.

 

So that's the background info out of the way and here is what I have made decisions on so far.

 

Lintel to be a expamet pre stressed reinforced concrete lintel as in link http://www.diy.com/departments/expamet-pre-stressed-reinforced-concrete-lintel- l1200mm-w100mm/150791_BQ.prd

 

Lintel specs:

Height     65mm
Length     1200mm
Width     100mm

 

The existing hallway door which sits in the ground floor load bearing wall also has a reinforced concrete lintel so I made assumptions that that would also be adequate for the new opening which is by the way a standard doorway with a planned cut out width of 82cm.

 

Moving onto the pad stones, I plan on cutting one of these to create the pad stones http://www.diy.com/departments/expamet-pre-stressed-reinforced-concrete-lintel-l900mm- w100mm/150788_BQ.prd

 

I decided this route for the pad stones as the pre made pad stones came in at nearly £30 each and the to be cut up lintel is only £9

I will seat these either side for the lintel on a bed of mortar and as these are only half the height of the existing blocks so I will have 2 each side.

 

Mortar mix - should I buy pre mixed?
Should I buy a Mortar Gun to force the mortar into the gaps, have read that mortar needs to be quite thick for lintel installs so may not apply very well from the gun?

 

I have read about packing the space above the lintel with slate so I plan on using the following https://www.travisperkins.co.uk/Estillo-5-Prime-Spanish-Slate-6-8mm-x-250mm-x-500mm/p/763823

 

I will be using acros with strong boys as my set up for supporting the above load although the only location for the spines is quite close to the ceiling so its going to ruin my coving but hey.

 

I'm using a reciprocating saw with a giant masonry blade for the cutting of the hole.

 

That's it so far but I'm sure as I get closer to the job in a few days I will start doubting other ideas as I always do.

Ta guys

 

 

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By the time you cut through the small amount of blockwork above the door, allowing for the lintel, there's not going to be much left of it to hold the floor joists above from strongboys.
 I would be inclined to prop it with planks and standard acro's under the ceiling very close to the wall on both sides. Perhaps as well as the strongboys?

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1 hour ago, ProDave said:

By the time you cut through the small amount of blockwork above the door, allowing for the lintel, there's not going to be much left of it to hold the floor joists above from strongboys.
 I would be inclined to prop it with planks and standard acro's under the ceiling very close to the wall on both sides. Perhaps as well as the strongboys?

 

ProDave I was just about to up my Acro rental count so as to enable your suggestion :D

 

Ta

 

 

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1 hour ago, Mr Punter said:

As it is only a 65mm lintel (are you happy it is man enough?) you can just use engineering bricks for the ends.

 

As per @ProDave acros and planks.

 

Hey Mr Punter What would be a good upgrade to my lintel choice? I am happy to be over cautious.

 

I was going to use engineering bricks but couldnt find any online at Wickes, TP, Tradepoint....blah blah

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56 minutes ago, Mr Punter said:

You can get a lintel 100 x 140 x 1200 like http://www.builderdepot.co.uk/concrete-lintel-textured-pre-stressed-100mm-x-140mm-x-1200mm.html which may be sensible for supporting the floor above.

 

Engineering bricks are http://www.builderdepot.co.uk/class-b-engineering-brick-smooth-red-b101.html

So its OK to use class B engineering bricks as padstones, happy days

 

Thanks Mr Punter

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Could anyone shine some light on a good mortar mix/ ratios for a lintel install? should I buy pre mixed? good brands such has Blue Circle?

 

I have never mixed mortar before so even the simplest tips are good;)

 

Cheers

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3 minutes ago, PeterW said:

4:1 by volume will be fine - don't be tempted to use rapid set ..!

 

you can buy the bags but they are usually slightly weaker. 

Cheers PeterW, Would that ratio mix be soft enough to use with a mortar gun so as to push the mortar into the gaps?

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Shouldn't need it really - blocks will hold up, butter the lintel well and the wedge it into place. 

 

You are leaving enough space to get the frame in with some room for alignment aren't you ..?

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2 minutes ago, PeterW said:

Shouldn't need it really - blocks will hold up, butter the lintel well and the wedge it into place. 

 

You are leaving enough space to get the frame in with some room for alignment aren't you ..?

Yup, the outside measurement of the frame is 82cm width so I'm going to chop out at 84cm to give 10mm each side.

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11 hours ago, PeterW said:

Give yourself 25mm each side unless you can guarantee it's perfectly plumb ... 

25mm it is Peter as my record of "oh that's definitely plumb" isn't the best:D

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