New build with light gauge steel framework

[seaweednylon]

Hello,

First off thank you all for your generous information shared here and on other forums, it’s an amazing resource to have.

Despite all my forum trawling and having read Rod’s book, I have some questions that I can’t find answers to. Any light anyone can shed on these would be most gratefully received.

I’m renting a 20m2 space in an open plan warehouse and building a new, one-room writing/mixing studio (I make production music for a living). My neighbours in adjoining spaces are artists/artisans of various persuasions. Some of them would probably be bothered by drums/amps and some will make similar levels of noise themselves. My space is in the corner of the basement. The existing walls are made of mixed materials, some parts concrete, some brick, some plasterboard stud wall (in the sketchup drawing below you can see plasterboard marked in beige and concrete/brick in orange). The floor is concrete and the ceiling looks to me like concrete joists with smaller concrete blocks laid between them (I don’t know what this is called, I’ll share a photo below). The ceiling height is 3.7 metres and my floor area is roughly 5.6*3.3 metres. My plan is to build a standard two leaf system. I have a limited budget to devote to this as the lease is limited to three years, after which the space will get torn down, so I’m hoping to do the minimum necessary to achieve the isolation I want. I'm hoping two layers of air-tight 13mm plasterboard with reinforced stock "acoustic" doors and baffled air inlets/outlets will get me there.

1 - In France, where I’m building this (near Paris to be precise) they most commonly use light gauge steel studs for all non-load bearing walls (these guys https://www.leroymerlin.fr/produits/lot ... 43289.html). I’m hoping I can use this for my walls as it’s far cheaper than timber studs. Has anyone any experience working with this stuff for studio builds? My worry is that the walls (the biggest is 3.7m * 5.6m) might not be strong enough using this for the framework. And I’m really struggling to find information on whether the ceiling of my inner leaf can be built using it (ie will a 3*5m span hold up two layers of 13mm plasterboard). People have told me to look at the manufacturer’s websites but I can’t find anything that shows me load-bearing capacity for a DOUBLE layered plasterboard walls, only those for single layers. Or can I assume that as most “normal” walls will have a layer of plasterboard on BOTH sides, that my wall (with two layers on ONE side) will perform similarly? And finally, the doorframe. I’m planning to use pre-made doors and reinforce them. Do I need to build out the framework around the stock doorframe in timber rather than steel? This is where I’m most lost so any help greatly appreciated.

2 - Another common construction thing in France is to put "resilient tape" under the bottom of any stud framework (https://www.leroymerlin.fr/produits/ban ... 54246.html). I presume this is to reduce sound transmission between the wall and the floor. Does this sound worth the expense in my case?

3 - Where the original walls are made of plasterboard stud, I'm going to double them up with another layer of 13mm, such that the minimum density for any of my walls is double 13mm plasterboard. Does that make sense? Does my outer leaf being composed of mixed materials sound like it will pose any major problems, provided I seal up all the edges where they meet?

4 - The ceiling, those concrete blocks. They have small air gaps between them, when seen from below (presumably they have a slab above that seals them) where the air tightness of my outer leaf would be compromised. Has anyone encountered these before? I’m planning to fill them with sealant on my side. They are massive, but not air tight, hopefully the sealant will cure that?

5 - And finally, there are some pipes running across my space that can't be moved, one fresh water pipe at the back, and one soil pipe at the ceiling. I'll route the electrics to all come through one entry but these water pipes I'll just have to seal around. Any advice on that? The access to the rear of the soil pipe is not great. Is there an alternative to using expanding foam there? I'd love to avoid having to box around it.

I’ll leave it at that for now, those are my most burning questions. Thank you for reading, you're all great.

x

Sketchup

The space

The ceiling/soil pipe

[gullfo]

assuming the walls are not load bearing, the metal framing should suffice. you can also consider adding a layer of OSB or plywood before adding the drywall. this will stiffen the assembly provide fastening options for the drywall and finishes.

for the pipes - you should build a soffit around them and use the same strategy as the walls - OSB/Ply 2x drywall.

as far as the resilent tape - if it's similar to something like the Kinetics Noise Wallmat product, it would be useful.

[seaweednylon]

Thanks Glenn! Yeah, I think boxing in the pipe is the only way to guarantee that i'm sealing up the room.

I have finally worked out what the manufacturer's guidelines for those kinds of walls are, in case anyone else is looking for them. Most of the different manufacturers have something similar to this https://www.placo.fr/lintegrale-placo which gives guidelines for all sorts of walls of different thicknesses with maximum heights for each. And the mass-air-mass kind of wall that I'm building is aptly called a SAD cloison in French (I think), or a separative cloison. The max height for these kinds of walls, using M48 rails and M48 montants doubled back-to-back and spaced every 40cm, with two layers of BA13 on one side of the wall is 3.05m. Given how much more expensive it would be to build it using M70 montants and rails I'm going to try it with M48 and reinforce it as much as possible from behind (using fourrures?) and to the column and ceiling where I have room to do so.

[gullfo]

the key for your space isolation is to ensure the new framing is decoupled from the walls and using isolation sway bracing to stabilise tall walls whe nyo ucannot use decoupled anchors in the floor AND ceiling (as well as back to back walls). it's ok if the insulation touches across the space, but not the frames. leave at least 25mm gap between the frames.