RC Walls 1

[TSON]

An architect would like to put his radon barrier (DPM) through my RC wall. THey will seal around the bars with a bithutene.

I have not seen this before, but he said it is common.

IS he correct, the wall is all vertical no wind or moment loadings.

His argument is that it should be treated as a block wall ! I understand this but am concerned at interupting the bond of the concrete.

Any advice out there..


Thanks

TSON

 

[bjb]

I'm not entirely sure what you mean, but what the architect wants to do dosen't sound right to me. It seems to me that the integrity of your wall will be gone by disturbing the bond. I have never heard of this either. Is the barrier going thru the wall perpendicular, or does he want to cast it in the wall, essentially splitting the wall down it longitudinal axis? Is this a load bearing wall?

 

[TSON]

he wants to cut the bottom of the wall horizontally at floor level as you would in a block wall (his argument).

The wall is load bearing with precast floor slabs on the next two levels.

My prefered detail is for the radon barrier (DPM) to dress down the internal face of the wall.

This would cost more due to the increased labour and materials.

I made the argument that we would lose a bond in the concrete but he argued that they do it in blockwork and precast concrete buildings?

 

[archeng59]

I may not completely understand the question, but based on your question, it sounds like the architect wants to create a hole thru the wall near the base of the wall. is the opening rectilinear? how wide and tall is the opening? If the wall is several feet long and the opening width is a few inches, then the concrete wall will "arch" over the opening similar to CMU over a narrow opening. If the opening is almost as wide as the wall is long, I would not be willing to approve the opening. how is the wall reinforced? are there horizontal reinforcing bars that you know their locations? If so, you could check the wall as a beam spanning over the opening, with the lowest horizontal bars (bars closest to the top of the opening) acting as tension steel. If the wall will span over the opening and there is adequate wall on each side of the opening to support the "beam" reactions, the opening might be ok. there may be other circumstances that would prohibit the opening thru the wall that you have not described in your question.

 

[TSON]

thanks for that

it is not an opening, it is a damp proof membrane that runs under the floor slab and the architects wants to terminate it out side the building, it would be about 1.5mm thick so it will act as slip plane alone the full lenght of the wall

 

[archeng59]

got ya. sorry for the long winded crapola, then.

 

[valleyboy]

Normally the radon barrier would be present beneath the ground floor construction to prevent radon migration upward into the structure.

If you have an effective lapped and jointed DPM beneath the floor slab, why would you require an additional barrier within the wall construction?

VB

 

[37ed]

If your wall is back filled and a floor load is there from above, no way He would taik me into that one.
Ask him this:

1. what is going to keep your wall from walking off when you back fill?

2. how are you going to apply your rebar from the slab/footing into the wall without putting holes in the barrier in the first place? What's the point?
3. And if it's done all the time ask him where? Prove it.

Good luck
Ed

 

[TSON]

THANK YOU GUY

STAND MY GROUND SEEMS TO BE THE OPINION.

 

[DaveAtkins]

Can the dowels extend through the barrier, thus tying the wall to the footing?

DaveAtkins

 

[TSON]

yes they could, but they would have bond with the concrete for about 75mm where they are sealed

 

[phuduhudu]

If I understand right you have a wall which is dowelled into the footing so that should prevent it from sliding off. If the wall can be designed as a pinned base strut as with masonry walls (as the arch is suggesting) then there should be no problem. You certainly aren't worried about the wall lifting up with two stories load on it. The only problem would be if you require base moment capacity for the wall. What you do have to watch is the spec of the radon barrier to make sure that it can take the compression of the wall.

Carl Bauer

http://www.bauerconsultbotswana.com