Dry Pack

[turexy]

Hi,

Well first post here... I have my design for removing load bearing walls and inserting a universal beams. I can see on the project that I'm going to need 40mm dry pack mortar (1:3) between the beam and the wall above. I was trying to look through the forum what the dry pack is exactly but not 100% sure. Is is a mix of cement (any kind or some specific one?) with fine sand in ratio 1:3? Can you buy anything like this which is already pre-mixed (in Wickes, B&Q etc)? If not what cement and what sand I should use? Any links to the product pages will be much appreciated.

 

[tony1851]

Ordinary Portland Cement (OPC) and building sand. The sand should be damp, rather than dry, otherwise you will be attempting to pack powder into the gap.
40mm is a rather big gap for dry pack, though.

 

[turexy]

Thanks for the info, well that's what on the design, have look at the relevant section, hope I'm reading it right

 

[turexy]

Oh and just to confirm, only damp sand and cement, no extra water should be added yeah? What is the desired texture of drypack?

 

[tony1851]

Hi turexy;
You read it right, but the detail is rubbish.
Ask the person who drew it to explain how you ram in the dry pack when you can't get anything in between the top flange and the bottom of the joist to ram with.
The steel should be higher up, directly under the masonry.
Typical amateur detail.

 

[turexy]

Thanks Tony,

This is just a small detail of slightly larger project. It was done by a structural design office in Reading. Here are the remaining drawings, if you think this is still bit dodgy I'll talk to them on Monday

 

[^woody^]

Normally, you would put wet mortar on the beam and then push it up under the wall leaving a 10mm joint.

A 40mm is wrong

 

[pred]

Hi,

Well first post here... I have my design for removing load bearing walls and inserting a universal beams. I can see on the project that I'm going to need 40mm dry pack mortar (1:3) between the beam and the wall above. I was trying to look through the forum what the dry pack is exactly but not 100% sure. Is is a mix of cement (any kind or some specific one?) with fine sand in ratio 1:3? Can you buy anything like this which is already pre-mixed (in Wickes, B&Q etc)? If not what cement and what sand I should use? Any links to the product pages will be much appreciated.

I have a few concerns about what you want to do, Are you doing it yourself? If you have to ask basic question as to what sand mix to use I have severe reservations about your skills, there are far to many accidents in the building industry, KNOW YOUR LIMITATIONS!

You can't just rip out a load bearing wall, you require acro props and boots or a few props either side taking the weight of the floors above, minimum four acros, two with boots for a small aperture and as woody says put a bed of muck on top of the lintel then wind it up with the other two acros and bed the lintel in on the pad stones.

 

[turexy]

Helo Pred,

I fully understand your concerns and NO I'm not going to do this myself I wouldn't dare. The project will be handled to builders but I'm the kind of person who like to know stuff. I was just looking at the drawings and I was curious what is what and how, hence my basic questions here.

 

[pred]

Helo Pred,

I fully understand your concerns and NO I'm not going to do this myself I wouldn't dare. The project will be handled to builders but I'm the kind of person who like to know stuff. I was just looking at the drawings and I was curious what is what and how, hence my basic questions here.

That's a relief, take my advice, your curiosity should firstly be to ask the builders; tea or coffee, you look after them and they'll look after you, you would be amazed how far a few doughnuts will go.

 

[tony1851]

you would be amazed how far a few doughnuts will go.

Depends how he makes the holes

 

[jeds]

fine sand in ratio 1:3? Can you buy anything like this which is already pre-mixed...

Not fine sand! It should be sharp building sand. It needs to be fairly dry - so a handful of mix squeezed in your fist holds together in a ball. There are premixed grouts available and they have the advantage of being non shrink. I doubt you'll find them in B&Q. Travis would have them. As Tony says It's not clear how you are going to pack that beam with the joists running alongside?

 

[^woody^]

From that section AA, the wall will be propped from above the joists and the brickwork in between the joists will drop out anyway. Making good will be done from above and the packing will be above the upper floor level not between the joists, as in that nonsense drawing

Otherwise packing is as described in post #7

 

[turexy]

Thanks guys for your advice, I'll take it to my structural engineer and as for some explanations.