Hollowcore Wrap or Tape?

DeeJunFan

Hi,

Have been speaking to some air tightness people and was discussing the wrapping of hollowcore slabs and was told that another option would be to tape the slabs top and bottom.

Not sure if this would be as air tight as wrapping the slab but it would be much easier to manage as i wont be on site at all times. It would also reduce the chance of damage to the slab air tightness (during fitting or before fixed above).

Any Thoughts?

Thanks
Damian

BryanF

wrap it! - taping top and bottom means you will not have air-tightness continuity.

1. why would it mater if your on site or not?
2. have you employed a contractor to build your house and set an air-tightness rate in the contract documents?
3. what has your architect stated?
4. and is the air-tightness person that is telling you to tape it top & bottom responsible for achieving the per-determained leakage rate?

sydthebeat

DeeJunFan wrote: »

Hi,

was told that another option would be to tape the slabs top and bottom.

just wondering if you have ever seen concrete slabs in situ on a site ??
if you had you would immediately see the problems with trying to do this.

DeeJunFan

BryanF wrote: »

wrap it! - taping top and bottom means you will not have air-tightness continuity.

1. why would it mater if your on site or not?
2. have you employed a contractor to build your house and set an air-tightness rate in the contract documents?
3. what has your architect stated?
4. and is the air-tightness person that is telling you to tape it top & bottom responsible for achieving the per-determained leakage rate?

I'm doing a self build, direct in northern ireland. There will be no contractor just individual trades.

Architect hasn't said anything about air tightness yet.

And no air tightness person isn't responsible for anything was just in contact and giving informal advice.

That's the reason I was wondering as I hadn't heard of that approach before.

Thanks

DeeJunFan

sydthebeat wrote: »

just wondering if you have ever seen concrete slabs in situ on a site ??
if you had you would immediately see the problems with trying to do this.

Have seen them on site. Was assuming the tape would be applied after grouting. The guy said they would seal the joints below with air tight sealant and then tape below.

Had never heard of anyone doi g it so was curious.

Thanks

rockabaloo

The problem you'd have with that approach is the outside air would make it into your cavity and then into the gaps between your hollowcore slabs.

Taping the slabs top and bottom would stop the air getting into the rooms at that point but because the air would be free to roam around all the slabs it could make its way into rooms at any penetrations top and bottom.

If you wrap the slabs you can have as many penetrations in this layer as you like with no airtightness concerns. There will be a lot of electric and plumbing penetrations in this layer.

DeeJunFan

rockabaloo wrote: »

The problem you'd have with that approach is the outside air would make it into your cavity and then into the gaps between your hollowcore slabs.

Taping the slabs top and bottom would stop the air getting into the rooms at that point but because the air would be free to roam around all the slabs it could make its way into rooms at any penetrations top and bottom.

If you wrap the slabs you can have as many penetrations in this layer as you like with no airtightness concerns. There will be a lot of electric and plumbing penetrations in this layer.

Thanks for that. makes much more sense.

I wasn't sure it would be as air-tight it was just something that had come up in conversation.

There have been a few threads on wrapping the slab and things going wrong and the wrap being damaged so i was just trying to gauge if the tape could be as robust a detail as it would be easier to put in and there would be less chance of damage etc.

Thanks again
Damian

hexosan

Have you priced the tape that way would cost a fortune.

DeeJunFan

So Overall not a good idea.

The tape was around 1.50 per m