Block and beam floor buildup for insulation?

[puntloos]

Well, the subject really says it all, how would you build a B&B floor? 

Goal: airborne sound primarily. Not intending to make 'dead' rooms (no recording studio/cinema), just trying to separate different people and their stereos jackhammers etc from each other ?

Here's one suggestion I found;

 

10mm Rubber crumb mat

20mm levelling screed

150mm Block & Beam

(acoustic hangers)

150mm MF Suspended ceiling

50mm Mineral wool

12.5mm Soundboard

 

= 400mm or so. 

 

[source]

 

Thoughts? Would this make a good ceiling regardless of insulation? Note that the underside also needs to fit some services, electrics etc.

 

 

 

[Moonshine]

Are you trying to stop noise from below upwards? Downwards or both?

[puntloos]

1 hour ago, Moonshine said:

Are you trying to stop noise from below upwards? Downwards or both?

 

Both is ideal, but below to up is much more important

[Moonshine]

You are.pretty much there in terms of what you are propsing

It maybe worth putting a isolated board above the levelling compound such as screedboard or a chipboard alternative.

May as well go 100mm mineral wool and two layer of 15mm soundbloc for shits and giggles.

 

Edit, use dense block in the floor

Edited April 19, 2021 by Moonshine

[Gus Potter]

All looks a bit odd structurally. 150mm beams then 150mm of suspended ceiling then more..up to 400mm.. lots of fixing / labour detail, then service penetrations to consider.

 

For a DIY self builder consider the price a local builder will charge to install all of this. If you have noisy kids.. then they won't be around for ever.. also, if too noisy just stop feeding them, could be much more cost effective.

 

 

 

 

[puntloos]

On 19/04/2021 at 23:39, Moonshine said:

You are.pretty much there in terms of what you are propsing

It maybe worth putting a isolated board above the levelling compound such as screedboard or a chipboard alternative.

May as well go 100mm mineral wool and two layer of 15mm soundbloc for shits and giggles.

 

Edit, use dense block in the floor

 

 

Thanks @Moonshine - so to confirm:

 

10mm Rubber crumb mat (Will this be OK for UFH?)
20mm Screedboard https://www.cellecta.co.uk/product/screedboard-201/ perhaps?

20mm levelling screed + UFH embedded in this

150mm Dense Block & Beam (acoustic hangers)

150mm void

100 mm Mineral wool

12.5mm Soundboard

 

not sure where you intend to use the 'two layer of 15mm soundbloc' in this?

 

fwiw in my current design I have 462.5mm to play with (so the above works..). Else I'd have to raise my roof. Not easy  

 

On 19/04/2021 at 23:53, Gus Potter said:

All looks a bit odd structurally. 150mm beams then 150mm of suspended ceiling then more..up to 400mm.. lots of fixing / labour detail, then service penetrations to consider.

How so, @Gus Potter? How would you make it.. less odd? Of course I'm sure  punching through various layers is harder than through a single layer, but the added price shouldn't be end-of-the-world?

 

On 19/04/2021 at 23:53, Gus Potter said:

For a DIY self builder consider the price a local builder will charge to install all of this. If you have noisy kids.. then they won't be around for ever.. also, if too noisy just stop feeding them, could be much more cost effective.

 

True, or just maybe wrap the sound insulating material around the kid rather than in the floor? 

 

 

[Gus Potter]

Hi Punloos.

 

It is the depth of the 150mm beams that flagged at my end. Below is a screen shot from the Millbank load span tables. Your imposed load for a domestic floor is 1.5kN/m^2.

 

Beams of this depth are fairly sensitive to deflection, vibration so that made me wonder. Also, as you have plenty floor depth to work with I wondered why the beams were so shallow in depth. 

 

Just to get a feel for this you can see that a 150mm beam will give you a rough span of 3.5m  (11 -12 feet), you may be able to squeeze a bit more if you reduce the dead load (srceed etc).. but at conceptual stage you don't want to be cutting things too fine as you have to deal with service openings, stair wells maybe and the odd point load.

 

Your starting point here is to look at the largest span you have, that may be in a big open plan area. Next look at the most common span.. say the main bedrooms. Then for beam and block look at what depth of beam will suit most rooms. Off the back of that you can develop up your sound insulation and any fire protection.

 

Next have a look at how you deal with the large span and how you may detail / design this. You also want to have a look at the walls and found construction just to check you have not backed the wrong horse in terms of capacity to support the loads, thermal bridging and acoustic detailing.

 

@Thorfun"True, or just maybe wrap the sound insulating material around the kid rather than in the floor? " Love to see you exploring all the design options.

 

 

 

 

 

 

 

 

 

 

 

 

 

[Thorfun]

14 minutes ago, Gus Potter said:

@Thorfun"True, or just maybe wrap the sound insulating material around the kid rather than in the floor? " Love to see you exploring all the design options.

I'd like to take credit for it but that wasn't me! ? 

[puntloos]

19 minutes ago, Gus Potter said:

Hi Punloos.

 

It is the depth of the 150mm beams that flagged at my end. Below is a screen shot from the Millbank load span tables. Your imposed load for a domestic floor is 1.5kN/m^2.

 

Beams of this depth are fairly sensitive to deflection, vibration so that made me wonder. Also, as you have plenty floor depth to work with I wondered why the beams were so shallow in depth. 

 

Just to get a feel for this you can see that a 150mm beam will give you a rough span of 3.5m  (11 -12 feet), you may be able to squeeze a bit more if you reduce the dead load (srceed etc).. but at conceptual stage you don't want to be cutting things too fine as you have to deal with service openings, stair wells maybe and the odd point load.

 

Your starting point here is to look at the largest span you have, that may be in a big open plan area. Next look at the most common span.. say the main bedrooms. Then for beam and block look at what depth of beam will suit most rooms. Off the back of that you can develop up your sound insulation and any fire protection.

 

Very good point, and not something I explored a lot. Clearly not enough.

My assumption was that any problematic loads can be handled with steel beams? 

 

In particular:

 

(ignore the weird kitchen wall layout, that's been resolved)

Largest span is 8m x 5m or 13m x 5m depending on if you include the kitchen. (there's no load above the dining room)

 

Currently I have 465mm for "the ceiling" 

 

Quote

Next have a look at how you deal with the large span and how you may detail / design this. You also want to have a look at the walls and found construction just to check you have not backed the wrong horse in terms of capacity to support the loads, thermal bridging and acoustic detailing.

 

To be clear of course an expert will need to validate all this, I'm just picking the 'preferred' layer buildups purely on acoustical and heat performance, the expert will need to see how to "reconcile" this into something that won't collapse if an overweight family member carries my kid into the bathroom

 

Quote

@Thorfun"True, or just maybe wrap the sound insulating material around the kid rather than in the floor? " Love to see you exploring all the design options.

Just trying for the optimal solution!

Edited April 25, 2021 by puntloos

[Gus Potter]

Hi Puntloos.

 

That living room is a chunk of space. Here are my thoughts on the layout you have provided. Much of this is SE related but I hope it gives you some pointers.

 

You have a pretty clear main rear elevation. If you look at the right side of the drawing you have a small return on the masonry, then a pier between W-05 and D-03, the access to the dining area and a long wall up the left side of the drawing.

 

SE wise this flags up how to stop the building moving from side to side in the plane of the rear elevation. Call this lateral stability.  Next you have this masonry pier between the two doors in the living room. Now, to make first floor economic over the living room it makes sense to span the joists from the internal masonry wall to the rear elevation. But in doing so you are going to add a lot of load to the pier as some of the first floor load will be carried by the lintels over the doors D-03 and W-05. You may well have some roof loads too and the weight of the second storey walls on the lintels.  From an SE view that pier is one of the key elements and I would have my doubts about the capacity of it.

 

Another thing that flags up is the length of the masonry wall on the left of the drawing. There are some stability issues here (as it looks like a long wall) and also at this size of house you'll need to detail and position the movement joints in the masonry to stop cracking. Good for cracking but not so good for strength as you introduce a discontinuity (weak spot) in the masonry which needs to be dealt with.

 

In summary there looks like a lack of "meat" in the masonry in terms of lateral stability and the pier capacity to carry the vertical loads. It could all turn complicated and nasty (expensive to build)) when you get down to the detailed calcs.

 

In SE terms there are a number of ways to design this but here are two concepts. Based on the drawing above.

 

Concept 1. In a couple of places you introduce two flat steel portal frames ie a double goal post. I would do these in the living room rear elevation as this keeps a clean line along the left elevation wall. These goal posts stop the building from moving sideways while also carrying the load from above. As an aside this would let you muck about with the door widths in the living room.. they may look good being symmetric?

 

Before progressing you maybe want to have a look at your budget and just how much you are able to spend on the acoustics. Maybe a reasonable compromise is in order here?

 

If you still want the full monty then I would look at a structural steel deck. Have a look at Kingspan Multi Deck for ideas. Here you get loads of mass for acoustics, fire protection. Also they are great for generating what we call "diaphragm action".

 

Option 2. To explain "diaphragm action" in laymans terms.

 

Imagine you get two carboard boxes and tape up all the sides. Put one on top of the other and tape them together. Now cut out the face (your living room doors) of the bottom box and tape the whole lot down to the kitchen worktop. Push it perpendicular to the cut door openings. just like your big living room doors. Look closely and you will see it stays up. The reason for this is that the uncut "gable" sides act to stabalise the boxes. The gables act in what we call "complimentary" shear, the uncut bottom wall of the box acts as a traditional "shear wall"... that would be your wall between the living room and the rooms at the bottom of the drawing.

 

Once you get a handle on the carboard boxes you could maybe use the metal deck as a diaphragm to transfer the shear loads to the wall at the bottom of the drawing and this wall will work with the gable walls... that is option 2 but the masonry will probably need to be 140 ~ 215 mm thick at least... looks like 215mm on your drawing anyway.

 

I hope this helps. Once you get a feel for how the thing stays up then you are well on your way. I would look to see if you can make you floors a bit thinner over all, add ceiling height thus value to the property. If you are building flats say and can make the floors thinner then at some point you can get an extra storey in while keeping the planners happy! Big bucks if in London.

 

The same may apply to you but on a smaller scale. Although I started out with an SE view hopefully this has a spin off on how you can go about getting the best for your money.

 

Lastly, all the best Puntloos.. the main thing is to keep asking questions, mull it over and enjoy the journey. Often you need to work out what you don't want as this helps narrow things down.

 

Oh and it's worth a punt doing the box thing as it may get the kids interested, engaged and consider exploring Engineering as a career.

 

But if not you could alway propose they invest in the build  (a cut in the pocket money) if they want to upgrade the acoustics in their own room?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Temp]

We have the following first floor..

 

Carpet

UFH in screed

80mm Insulation

150mm beams (100mm blocks and 50mm void)

Battens fixed to beams using supplied hangers

Plasterboard

 

In large living room two steels were used to reduce to span of the concrete beams. These were deeper than 150mm so the top is in the insulation.

 

Main issue we had was the BCO wanting us to use fire rated downlights which in the days of halogen bulbs only just fitted into the void.

 

Were happy with this but you can hear loud TV in living room below. 

 

[puntloos]

3 hours ago, Gus Potter said:

Hi Puntloos.

 

That living room is a chunk of space. Here are my thoughts on the layout you have provided. Much of this is SE related but I hope it gives you some pointers.

 

You have a pretty clear main rear elevation. If you look at the right side of the drawing you have a small return on the masonry, then a pier between W-05 and D-03, the access to the dining area and a long wall up the left side of the drawing.

 

SE wise this flags up how to stop the building moving from side to side in the plane of the rear elevation. Call this lateral stability.  Next you have this masonry pier between the two doors in the living room. Now, to make first floor economic over the living room it makes sense to span the joists from the internal masonry wall to the rear elevation. But in doing so you are going to add a lot of load to the pier as some of the first floor load will be carried by the lintels over the doors D-03 and W-05. You may well have some roof loads too and the weight of the second storey walls on the lintels.  From an SE view that pier is one of the key elements and I would have my doubts about the capacity of it.

 

Agreed, as amateurs and architects (no SE involved just yet... ha you're our first... ) we already were thinking about that one.

Note that the updated version of the house looks more like this:

  

 

My own design, but in particular note that the external wall is much thicker:

435mm:

skim 5mm
sandcement plaster 15mm
medium block 100mm
EPS blown beads (with stainless steel wall ties perhaps) 200mm
medium block 100mm
sand cement render 15mm 

 

But perhaps more importantly, split the large glass pane into two much more modest windows.

 

Would your suggestion of the 'portal frames' still hold? My pier design and location is somewhat more central to the main area.

3 hours ago, Gus Potter said:

Another thing that flags up is the length of the masonry wall on the left of the drawing. There are some stability issues here (as it looks like a long wall) and also at this size of house you'll need to detail and position the movement joints in the masonry to stop cracking. Good for cracking but not so good for strength as you introduce a discontinuity (weak spot) in the masonry which needs to be dealt with.

 

Something I will certainly flag with the SE.. 

 

3 hours ago, Gus Potter said:

In summary there looks like a lack of "meat" in the masonry in terms of lateral stability and the pier capacity to carry the vertical loads. It could all turn complicated and nasty (expensive to build)) when you get down to the detailed calcs.

 

In SE terms there are a number of ways to design this but here are two concepts. Based on the drawing above.

 

Concept 1. In a couple of places you introduce two flat steel portal frames ie a double goal post. I would do these in the living room rear elevation as this keeps a clean line along the left elevation wall. These goal posts stop the building from moving sideways while also carrying the load from above. As an aside this would let you muck about with the door widths in the living room.. they may look good being symmetric?

 

Before progressing you maybe want to have a look at your budget and just how much you are able to spend on the acoustics. Maybe a reasonable compromise is in order here?

 

How much do you think going from "bog standard" to "fancyacousticsomg" willl cost per square meter, purely materials wise? I imagine I'm living in an area where the labour and just 'location' costs more than raw materials, for most intents and purposes

 

 

 

3 hours ago, Gus Potter said:

If you still want the full monty then I would look at a structural steel deck. Have a look at Kingspan Multi Deck for ideas. Here you get loads of mass for acoustics, fire protection. Also they are great for generating what we call "diaphragm action".

 

We've already assumed block and beam flooring so multideck doesn't even have to be *that* much more expensive. Of course money is important but I'm more concerned about my house 'sandwich' will grow above what I have planning permission for. Currently my ceiling height is 2.7m (ground) and 2.4 (1st) and 2.3(loft) 

3 hours ago, Gus Potter said:

Option 2. To explain "diaphragm action" in laymans terms.

 

Imagine you get two carboard boxes and tape up all the sides. Put one on top of the other and tape them together. Now cut out the face (your living room doors) of the bottom box and tape the whole lot down to the kitchen worktop. Push it perpendicular to the cut door openings. just like your big living room doors. Look closely and you will see it stays up. The reason for this is that the uncut "gable" sides act to stabalise the boxes. The gables act in what we call "complimentary" shear, the uncut bottom wall of the box acts as a traditional "shear wall"... that would be your wall between the living room and the rooms at the bottom of the drawing.

 

Once you get a handle on the carboard boxes you could maybe use the metal deck as a diaphragm to transfer the shear loads to the wall at the bottom of the drawing and this wall will work with the gable walls... that is option 2 but the masonry will probably need to be 140 ~ 215 mm thick at least... looks like 215mm on your drawing anyway.

It is, so that should be okay.. and indeed the metal deck might be the way to go..  

 

But, as it stands I was planning:

 

soundbloc plasterboard (15mm)
block(75mm)
vertical battens w/ rockwool (25mm)
block(75mm)
soundbloc (15mm)

 

(but not really 'solid' design yet - the main point is noise insulation again, but especially I imagine that central wall to carry the entire house, so to speak, so perhaps it needs to be thicker, which would be fine, eg:
 

soundbloc plasterboard (15mm)
block(100mm)
vertical battens w/ rockwool (25mm)
block(100mm)
soundbloc (15mm)

 

[Gus Potter]

Hi Puntloos.

 

Copied some extract from your last post in italic and added my thoughts.

 

"My own design, but in particular note that the external wall is much thicker:

435mm:

skim 5mm
sandcement plaster 15mm
medium block 100mm
EPS blown beads (with stainless steel wall ties perhaps) 200mm
medium block 100mm
sand cement render 15mm 

 

But perhaps more importantly, split the large glass pane into two much more modest windows.

 

Would your suggestion of the 'portal frames' still hold? My pier design and location is somewhat more central to the main area.

 

The piers don't contribute as much as you would like to the horizontal stability, unless you have plenty load coming down from above to assist in resisting the overturning moment from the wind. With a 435 thick external wall it kind of rules out some kind of portal frame with a bottom shelf angle to support the external leaf as you probably generate too onerous a torsional moment (twisting effect.. does not interface well with glazing) which will cause problems, not least with the portal connections given the space you may have to form said connections.

 

It may work well with a portal for the inner leaf (deals with the horizontal stability) which will carry the first floor and roof loads and some off the shelf lintels to support the outer leaf. If you can decouple the inner and outer steel it makes it a bit easier to deal with the thermal bridging.

 

 

 

 

 

[puntloos]

@Moonshine

An update - my architect suggests:

 

75mm screed with underfloor heating

20mm PIR insulation (this can be a high performance one such as Celotex TB4000)

5mm Regupol resilient layer (acoustic underlay)

150mm beam and block

150mm void

100mm mineral wool insulation

12.5mm SoundBloc plasterboard (you can use two layers for enhanced acoustics)

 

Would that be sensible?

 

On 29/04/2021 at 22:11, Gus Potter said:

Hi Puntloos.

 

Copied some extract from your last post in italic and added my thoughts.

 

"My own design, but in particular note that the external wall is much thicker:

435mm:

skim 5mm
sandcement plaster 15mm
medium block 100mm
EPS blown beads (with stainless steel wall ties perhaps) 200mm
medium block 100mm
sand cement render 15mm 

 

But perhaps more importantly, split the large glass pane into two much more modest windows.

 

Would your suggestion of the 'portal frames' still hold? My pier design and location is somewhat more central to the main area.

 

The piers don't contribute as much as you would like to the horizontal stability, unless you have plenty load coming down from above to assist in resisting the overturning moment from the wind. With a 435 thick external wall it kind of rules out some kind of portal frame with a bottom shelf angle to support the external leaf as you probably generate too onerous a torsional moment (twisting effect.. does not interface well with glazing) which will cause problems, not least with the portal connections given the space you may have to form said connections.

 

It may work well with a portal for the inner leaf (deals with the horizontal stability) which will carry the first floor and roof loads and some off the shelf lintels to support the outer leaf. If you can decouple the inner and outer steel it makes it a bit easier to deal with the thermal bridging.

Nice, different topic - I've forwarded that to the architect too btw

[Temp]

We have a B&B first floor with UFH. Think the make up is...

 

75mm UFH in screed

80mm PIR (would use more now)

B&B Floor 150mm beams with 100mm blocks (so 50mm void between beams)

Battens on clips supplied by B&B company

Plasterboard.

 

The combined depth of plasterboard, batten and 50mm void was just enough for Fire and Part E rated downlights.

 

Our SE recommended using two steel beams in our largest room to reduce the span that the concrete beams needed to cope with. Thses steels are deeper than 150mm so the tops project into the 80mm PIR. I can make a sketch if thats not clear.

 

 

[puntloos]

4 hours ago, Temp said:

We have a B&B first floor with UFH. Think the make up is...

 

75mm UFH in screed

80mm PIR (would use more now)

Why so much thermal insulation though? Between ground and first, is it a major problem for heat to transfer somewhat (I assume the rising air will carry much more?)

 

4 hours ago, Temp said:

B&B Floor 150mm beams with 100mm blocks (so 50mm void between beams)

OK so that's the same as our design

 

4 hours ago, Temp said:

Battens on clips supplied by B&B company

Plasterboard.

 

The combined depth of plasterboard, batten and 50mm void was just enough for Fire and Part E rated downlights.

 

Our SE recommended using two steel beams in our largest room to reduce the span that the concrete beams needed to cope with. Thses steels are deeper than 150mm so the tops project into the 80mm PIR. I can make a sketch if thats not clear.

 

 

If you have a moment I'd love a sketch, yes.

[Temp]

15 hours ago, puntloos said:

Why so much thermal insulation though? Between ground and first, is it a major problem for heat to transfer somewhat (I assume the rising air will carry much more?)

 

Obviously insulation is more important on the ground floor but we ended up using same on both. The upstairs rooms are empty in the daytime and our installers suggested using the same to get a good response time. 

[Temp]

This is roughly what ours looks like. Above our living room we have a pair of steel beams to reduce the span of the concrete beams. The concrete beans are inverted T section and sit on the bottom Flange of the steel beam.

 

We wern't too worried about noise transmission and it hasn't been a problem for us. If we had wanted to improve it then I guess we could have replaced or added resilient bars to the battens,  filled the void with sound insulation and possibly used two layers of plasterboard?

 

In our bathroom we omitted the insulation and screed where the shower tray was going. The shower tray rests on a  2x4 frame with WBP on top. The thickness of the insulation and screed helped with the falls from the shower trap to stack.

 

[Temp]

This is what our shower section looks like. We opted for a stone tray with frameless shower panel and door as we don't like wet rooms.  We set the inside of the tray flush with the floor so the lip/rim is higher. If you set the top of the tray flush the door seal can scrape in the tiles if it open out. Lots of ways to skin this cat.

 

 

 

 

 

[puntloos]

Reviving this thread after yeaaars.. (it's aliiiive)..

 

So for livingroom wall:

 

soundbloc plasterboard (15mm)
block(100mm)
vertical battens w/ rockwool (25mm)
block(100mm)
soundbloc (15mm)

 

=255mm

 

We'd prefer to cut it down a little, but is this - in principle - a very good insulating buildup? (assuming the SE agrees it'll carry enough weight)?

 

(preference is 75mm blocks)

 

[joth]

6 hours ago, puntloos said:

So for livingroom wall:

 

Just to check, this topic was previously about floor build up, but you're asking about internal walls now?

Not that I have any thing to add, but /interested 

[Iceverge]

We have 215mm blockwork with 20mm wet plaster on both sides between our living rooms and some of the bedrooms. You can't hear anything through them. 

[puntloos]

33 minutes ago, joth said:

 

Just to check, this topic was previously about floor build up, but you're asking about internal walls now?

Not that I have any thing to add, but /interested 

Yeah, the conversation drifted into internal walls back then, and that bit wasn't answered

 

26 minutes ago, Iceverge said:

We have 215mm blockwork with 20mm wet plaster on both sides between our living rooms and some of the bedrooms. You can't hear anything through them. 

215mm? That's.. a lot of block. No air gap between them?

[Iceverge]

Yup, just standard blocks on their side. 

 

[Temp]

19 minutes ago, puntloos said:

Yeah, the conversation drifted into internal walls back then, and that bit wasn't answered

 

He's probably built it by now.

 

We went for a regular B&B floor with insulation and UFH in screed on top. Some rooms carpet, some wood floor, some tiles. Underneath the B&B co provided hangers for battens and plasterboard. No soundproofing insulation added.

 

My kids were about 5 when we moved in and are 21 now. They weren't the most noisy kids but we never really had a problem with noise. 

 

I think if you wanted to improve it I would replace the battens with resilient bars (?) fit sound insulation and perhaps double up the plaster board?