New build small size high isolation project

[Purelythemusic]

Hi All,

I'm so glad I've got on this boat.

I'm building a new building the constraints of which are:

Final height and size - 2.6m high from surrounding ground level, size is 6m x 7m.
Trees nearby, soil type is high fines, Plasticity index 13% which is low, but there is clay below the test depth (we discovered). Some drainage pipes nearby but our load is not affecting that.

The building needs to incorporate sufficient storage for my tools (builder) and offer a suitable environment for recording, writing, practice and probably dancing if the aforementioned are successful (compact variety).

It is located at the bottom of my garden which belongs to the house I part own with my wife and her parents (4 way mortgage - a bold move but I like to think it is the best for all). We've spent the last year and a bit building a large extension and renovating the house to accommodate our separation, growing family and future material comfort (within reason).

My initial design was a combination of my existing acoustic knowledge (minimal) and a small degree of research into room shape etc. The John Sayers forum was the gateway to finding out my ignorance and at the same time, the correct way to approach the design phase.

With help from Stuart in particular I've started as on track as I can.

The building is set into the ground to enable a decent ceiling height and a good isolation design. It also mitigates the concern with trees having an influence on the water content of the soil supporting the structure, good all round apart from on the pocket. I haven't actually worked it out yet but the soil removal alone was around £5k Concrete was around £3.5k Labour was around £2k Plant hire about £600.

Here are some sketch up images of the basic isolation design followed by some construction pictures. I'm working on it full time-ish 4 days a week. We've (Me and me mate...a labourer comes when he comes...sometimes) just finished the 6th week of the job.

Outer wall sits on Strip footing...depth varied from 2.1m to 1.6m
Inner room sits on reinforced raft slab at 1.6m deep
Foundations are separated by clay heave board which is low density 50mm EPS (polystyrene)

The raft has an immense amount of steel reinforcement! half a ton.

The outer wall below ground is a 100mm dense block, 100mm cavity filled with concrete and 100mm dense block wall. Above ground it is a 215mm wide dense block wall (blocks laid flat). The outer roof is Block and beam 255 beams to span the ~6m with dense blocks infilled, grouted, then ~50mm concrete atop to seal and strengthen and of course add mass. Small parapet wall to match extension. Insulation (PIR) on top of flat roof concrete after Vapour membrane of course : ), concrete/screed on top. Liquid rubber roof 'Kemper system'.

Inner room is 215mm dense block wall, similar roof/ceiling design but no parapet, so concrete.

Cavity between leaves was planned to be 150mm but due to building troubles with trench collapse ect the strip footing has wobbled it's way into the raft space. We'll have over 200mm cavity on the 3 tightest walls. Ceiling to roof cavity is around 290mm. Cavities planned to be filled with Rockwool mineral wool.

I want to be able to play drums at midnight and someone walking down the lane, not be able to tell it's live/coming from a nearby room.

Ambient C weighted SPL has been measure at between 40 and 45db.

Intended Isolation target 70db...ambitious. The weakest parts have been identified as:

Build attention to detail not to connect the two leaves with accidental mortar management.
The two doors matching the isolation of the rooms leaves.
The HVAC silencers matching the isolation requirement.

The weather has been challenging, hence the need for a canopy. The unforseen swimming pool was from an old drainage pipe which is connected to the 1.3m diameter storm drain which runs down our lane and is connected to the nearby river...which should have a one was valve shutting at high tide...it doesn't. At the last spring tide we enjoyed flooding of the construction, luckily each time it happened the mortar had set up enough not to be washed away!

[Soundman2020]

Hey Tom.... I'm also glad you made it over to the new forum! Your build and your goals are very ambitious, but achievable if you do everything right... and so far, you certainly are. The photos show what you have a accomplished in a very short time, considering it's just you basically, with help occasionally.

The completely isolated leaf design is going to be a big part of the outcome. It's not often that people go to that extreme, to isolate even the foundations. For those who didn't pay too much attention to your explanation, I'll repeat it here: the outer leaf sits on one foundation, and the inner leaf sits on a completely separate foundation, with no coupling at all between them (other than the soil that the both rest on). That's unusual, and guarantees that any vibration in the structure of the inner-leaf will not get into the outer leaf (and vice versa). This is how you get beyond the normal limits of a single-slab, which is what the majority of home studio builders are stuck with, because the slab itself does provide some slight coupling between the leaves. For most studios, that's fine, since they don't need high isolation, like Tom does. Isolating drums down to silence a few feet outside the wall is a big challenge. Drums can easily put out 115 dBC, and more, with a lot of that energy being in the low-mids and lows : thus, the hardest to contain. With ambient levels of around 45 dB around the location of the studio, Tom needs those 70 dB of isolation, just to get the drum level down to the same level as ambient. Ideally, he's looking for about 80 dB total isolation, to make it inaudible to folks walking past in the lane, a few meters away. At a distance of about 6 or 7 meters, away from the walls, it should be inaudible.

So, there's two different foundations, one for the outer leaf, one for the inner leaf. And each leaf is massive concrete blocks (including hte ceiling! Both outer.leaf roof and inner-leaf ceiling are concrete "beam-and-block".... And the air spring between them is also massive: 20cm (about 8"). In theory, the MSM resonant frequency is below 10 Hz, so the studio should isolate from 20 Hz upwards... and at typical drum frequencies, the isolation should be really good already.

70 dB isolation is an ambitious goal, for sure, but the way Tom is doing it is the right way, and it is achievable. In theory, he should get a little more than that, but when you are talking such high numbers, even slight imperfections in the materials or workmanship can rob you of something, so allowing for that, 70 dB is realistic.

The other issue Tom has, is that his place is in an area subject to flooding, so flood control is part of the design: the building is completely sealed for that, to prevent water getting in, and there are barriers he has to put place in front of the entry door to hold back the flood waters. There's also other precautions, such as for the HVAC compressor; normally that just sits on a small concrete pad outside the building for most studios, but that can't happen here, as it would be wiped out by the flood waters... so the compressor has to go up high, above the highest level for any conceivable flood. And all of the electrical, Internet, intercom ad other cables are buried underground, and sealed too.

And the other OTHER issue, is the soil type: it's not the best for supporting this type of construction, so the structural engineer insisted on over-designing the metal in the foundations, to make them a lot tougher than would normally be needed. Commonly, the tpe of foundation that a typical home studio sits on has made 2 or 3 pieces of rebar in it, and perhaps a bit of light steel mesh... sometimes. But here's what Tom's foundation metalwork looks like:

Yup! That's major steel! You could park a battleship on that foundation!

Oh, and as Tom mentioned: the building is partly sunk into the ground, in order to keep the visible roof level low enough to meet code, while still having enough interior room height for good acoustics.

So, like I said; this studio build is gonna be a wild ride! It's "to the extreme", in all senses.

So make sure you subscribe to this thread, and check back in regularly: Tom is going FAST here!

- Stuart -

[Purelythemusic]

Thanks Stuart, glad you could step in and make it happen correctly! Thanks for filling in the gaps too! Lets hope I can seal the deal accousticly!

[endorka]

What an incredible project, total respect. I don't think I've ever been in a studio with such acoustic isolation, not even high end ones.

I'm intrigued about the corridor running the full length of the building between the inner and out leaves. What was the reason for this as opposed to, say, a smaller soundlock?

Cheers,
Jennifer

[Purelythemusic]

Hi Jennifer,

Well its primary purpose is for storage of tools (builder) and music kit as the room is going to be used for a variety of purposes... going to make some reversible panels absorbers/reflectors/diffusers hopefully... if the budget isn’t completely exhausted : )

Thanks for your interest!

Tom

[sgleason]

Fantastic project! I have nothing to add....just watching and learning.

Steve

[Purelythemusic]

Hi All,

Had a fiddly week... did as much block work as the canopy frame would allow, then tanked the inside face of the outer wall up to damp proof course (just over 150mm higher than outside finished ground level at the highest point), in order to prevent the ground moisture to continue into the structure.

We also tanked the raft slab floor in a strip under where the new internal walls will be to prevent any rising ramp from the slab... the inside face of the inner wall will also be tanked.

I then began setting out and building the inner room walls on top of a plastic dpc to ensure full moisture barrier! We had some 450wide dpc so I laid this over the cavity join so when we are up to a height to install insulation (around 600mm) we can clean it all of any mortar drops and cut it back if needed. Mineral wool in, then continue block work with cavity ties (but not installed as normal ties, instead just projecting into cavity not touching outer wall, enough to support insulation above).

After tweaking the room size as big as I could fit on the raft we’ve ended up with internal dimensions of 5720 long by 3550 wide block to block.

Next week we should have scaffolding to raise the canopy enough to build the whole thing out of the rain, so the inner and outer walls can get to the first concrete roof height, which is the next biggest challenge!

Pics at the end of play today:

[Purelythemusic]

Oh two quick notes...

We’ve changed block supplier, the blocks we were using were varying in width by 5mm in some cases so one face of block work was flush the other was far from it. We are using nicer blocks now with crisp edges.

2nd point is the tanking below doc will ensure air tightness of the outer wall. I am planning to spray (using textured spray gun through compressor) masonry paint from doc upwards to seal the walls there. Unless anyone thinks there would be a better sealer to use!

[Starlight]

I am planning to spray ... masonry paint from doc upwards to seal the walls there. Unless anyone thinks there would be a better sealer to use!

I have read that painting walls ensures that they are airtight and that can sometimes add an extra couple of dB TL. Masonry paint sounds to me like a wise choice.

[Avare]

Looks great! I am not going to wish good luck because you are doing it right and luck has nothing to do with that.

[sgleason]

2nd point is the tanking below doc will ensure air tightness of the outer wall. I am planning to spray (using textured spray gun through compressor) masonry paint from doc upwards to seal the walls there. Unless anyone thinks there would be a better sealer to use!

CNRC does speak of porosity of the block as the determining factor for improvement.

http://www.soundivide.com/uploads/conte ... eng-46.pdf

[Purelythemusic]

Hi All,

Thanks Avare! I remember your contributions from GS!

Just a couple of pics from today, inner room coming up and rockwool in the cavity...which we cleaned. We are now using some 20mm thick cavity wide timber to catch mortar drops to reduce any chances of mortar bridging the gap.

Oh and canopy off in anticipation of scaffold in a day or two! Dry weather forecast until Friday, scaff is due up on Thursday. We needed the canopy structure gone so we could raise the outer walls before the inner walls... so we could get them sealed...

Should be a strong week!

[Purelythemusic]

Hi All,

Got the outside wall built to a similar height as the inside ceiling height, then put up the cover in some manner as the scaffolding is delayed...as usual!

Spent the last couple of days on the inner room construction. We’ve run out of blocks as the merchant has had a supply issue. Should be restored for Tuesday next week so I’m planning to get the inside room up to height next week.

Heard today that the inner room beams should be with us next Friday which should tie in well. I’m banking on the delivery driver being able to lift them onto the roof!

Pics for the end of the week:

[Starlight]

Heard today that the inner room beams should be with us next Friday which should tie in well. I’m banking on the delivery driver being able to lift them onto the roof!

There are delivery drivers and delivery drivers. I hope it turns out well, whatever happens on delivery day.

PS. Nice photos; much appreciated.

[Purelythemusic]

Hi All,

Had an unfortunately windy and rainy night last night which ripped the cover and exposed the walls to rain. Not a structural concern but as we had applied the paint with the cover on and with all the moisture from drying mortar that had been trapped in by having the cover on, the paint hadn’t fully bonded and some has been rinsed off! I reinstated the cover for the last of the rain we’re due and have now removed it to allow it to dry as much as possible in the day time. At the moment we are having 4 or 5 degree nights with 10-12 degree days so I hope this is enough... I certainly can’t leave the cover on as it would just sweat and not improve! If the scaffolding had gone up when it was supposed to last week it would have been aired and dry!

I have peeled back some of the rockwool to see how much paint has been washed off and in most places it’s only washed some off above the rockwool, in one place it’s below. It is external masonry paint so I am a bit surprised it hadn’t dried in but it must just be too moist. Had I known the scaffold wasn’t going to come I may have applied something different like a slurry... very frustrating.

I’m planning to repaint where I can as taking walls down for it is not really an option!