Iso-Mount Type 2 Installation Guide - Option 3
Fixing directly onto a concrete ceiling. Creates a new isolated ceiling with a 50mm deep void for additional insulation.
Calculate the weight of the ceiling
Ceiling boards, downlights etc, insulation, plaster and add 10% for fasteners etc.
NOTE: There will be a movement of several millimetres as the weight of the ceiling sits on the Iso-mount rubber blocks: if ceiling height is critical allow for up to 5mm. Do not fit heavy items to the ceiling boards without the approval of the board manufacturer. Increase the amount of Iso-Mounts appropriately to support the additional weight.
The maximum loading of each Type 2 Iso-Mount is 18kg therefore 3 mounts per sq.mtr evenly spaced to spread the load, supports up to 54kg/sq.mtr.
A typical load calculation for 50mm void with insulation - kg/sq.mtr
2 x layers of 12.5mm (0.5 inch) @ 10kg each - 20
50mm of 50kg/cu.mtr mineral wool insulation - 3.0
2 x mtrs GL 1 'C' Channel - 0.5
3 x Iso-Saddles - 0.1
Fixings, tape and plaster - nominal - 0.9
Total - 24.5
Calculating the positions and quantities of Iso-Mounts
This is easier if done to scale on paper first but for a quick calculation take the square meterage of the room and multiply by 3 + 5% for the quantity of Iso-Mounts.
E.g. a 10m2 room x 3 = 30 + 5% = 32 Iso-Mounts
1. Decide which way you want the ‘C’ Channel to run.
2. The Iso-Mounts nearest the walls should be fixed at a nominal 100mm from the walls and no further than 150mm from the walls.
3. Divide the space equally between the mounts positioned at 100mm in from the walls. The above example has 5 equal spaces of 902mm. Reducing to 4 equal spaces would result in less than 54Kg/sq.mtr maximum loading capability.
When the Iso-Mount positions are marked drill pilot holes for accuracy.
Then drill a 6mm diameter hole 60mm deep and fix the ‘C’ Bracket to the concrete with a 7.5mm x 50mm EasyDrive Concrete Screw using an impact driver with a 5 ribbed tip.
Ensure the ‘C’ Brackets are firmly fixed and levels are satisfactory, use shims if necessary.
4. When all of the Iso-mount ‘C’ brackets are in position you are ready to assembly the other 2 components of the Iso-Mount: the rubber block and the saddle. Entry of these into the ‘C’ bracket is restricted so assemble the rubber block into position on the saddle first and then slide the assembly into position on the ‘C’ bracket.
THERE IS A TECHNIQUE to doing this which is quickly mastered, it involves compressing the rubber against the pronged upstands to achieve good location.
5. Once assembled and seating correctly slide the Iso- Peg into position, this will prevent the Iso-Mount coming apart when the ‘C’ channel is installed.
NOTE: The Iso-Pegs are removed after the ‘C’ Channel is installed.
6. Before Clipping the ‘C’ Channel Into Position
The ‘C’ channel clips into place in seconds but is difficult to remove if you find that you need to reposition some Iso-Mounts, you may have to cut a section of ‘C’ Channel away to allow the rest to slide off the hangers – if ‘C’ Channel becomes distorted don’t re-use it.
7. Check again that you are happy with the fixed positions of all the Iso-Mounts.
8. With the mounts in position fix the GL1 Channel.
Fixing the 'C' Channels
(Proprietary 48mm drylining channel)
These are the channels that the plasterboard will fix to with proprietary screws. Our preferred channel is British Gypsum GL1 and GL3 Channel connectors.
NOTE: Do not snap-fix the channel into position until you are satisfied it will not have to be removed again.
NOTE: The ends of the ‘C’ Channel must be no closer than 20mm (0.75inch) to the walls: the ceiling does not touch the walls, this could transmit sound.
**Image pending - drawing 11 Iso-Peg and ‘C’ Channel**
1. Place Iso-Pegs between the top of the saddles and the ‘C’ brackets to hold the saddles in position whilst the ‘C’ channel is clipped on.
2. Hook a length of C Channel onto 1 side of the saddle of 2 Iso-Mounts that are at least 1 metre apart, then squeeze the C Channel and saddle between your thumb and fingers and the channel will snap-fix into position.
3. Repeat this along the rows of fixed Iso-Mounts.
Finally check that:
- The fixed C Channel is level and clear of the walls at both ends
- The Iso-Mounts are still correctly assembled
- The Iso-Pegs have all been removed
Fixing Oscar Foam
This fixes around the walls and the plaster board abuts to it, isolating the soundproof ceiling.
1. Mark a horizontal line around the wall at the calculated level of the underside of the floating ceiling, i.e. level with the underside of the plasterboard. When using 2 layers of 12.5mm plasterboard this will be 25mm, (1 inch), below the underside of the ‘C’ Channels.
2. Install 25mm wide x 10mm thick (1x3/8”) self-adhesive Oscar Foam along this line with the bottom of the foam on top of and sitting 5 mm (3/16 inch) above the line – this allows for the foam to distort when compressed by the plasterboard and space for a bead of Oscar Seal flexible acoustic sealant.
NOTE: This will prevent direct contact between the plasterboard, and the wall: a potential path for vibration and noise transfer. Oscar foam and the Oscar Iso-Mount combined create the floating soundproofing ceiling.
Installing the insulation
*For smaller areas*
High density (60Kg/cu.mtr (3.75Lbs/cu.ft) or higher) mineral wool slab.
- Can be purchased locally to the job.
- Can be cut with a wood saw.
- Does not require specialist installation machinery.
1. Order material to completely fill the depth of the void, it is available in slab form in various thicknesses.
2. Cut the width to be a tight fit between the ‘C’ channels, butt joints tightly and fill all gaps.
3. To hold the boards in place use small right angled steel 'L' brackets.
Fixing the plasterboard
Fix the first layer of 12.5mm plasterboard with 25mm (1inch) drylining screws which will self-tap into the ‘C’ channel - Do not position screws under the joists or the Iso-Mounts where they may make contact and form a path for sound transmission. Keep the outer boards compressed into the Oscar Foam at the perimeter of the room. Keep gaps to the minimum and seal gaps with Oscar Seal.
For best results fix a second layer of plasterboard repeat the operation but stagger joints and use 38mm (1.1/2inch) drywall screws, Seal gaps with Oscar seal keeping level or below the surface of the board, then tape and joint the ceiling ready for plastering.
Plaster to the walls, i.e. plaster over the Oscar Foam that runs around the perimeter of the ceiling separating the acoustic ceiling from the walls.
Before the plaster is fully dry run a flat trowel or blade flat against the wall and through the new plaster to create a gap of 3mm minimum and break all direct contact between the new ‘floating’ ceiling and the walls
When the plaster is dry, tidy any nibs caused by creating the gap and seal the gap with Oscar Seal. Oscar Seal is an intumescent flexible acoustic sealant that can be painted over when dry.
A recycled non-hazardous cellulose insulation that is blown into the void with specialist machines.
- The best performing acoustic insulation
- Non itchy
- Fire retardant
- Up to 85% Recycled
- The lowest embodied energy (the energy used to manufacture) in the insulation industry
- Blown into the void completely filling all gaps
- A very effective thermal insulator and where there are multiple habitations very little heat energy will be lost to adjoining units. Thermal transmittance through a typical ceiling will be better than U = 0.20W/m2K
- Very economical for larger areas
- Holiday Inn, Sheraton and Intercontinental Hotels use Celbar ceiling and wall insulation for minimum sound transmission between rooms ensuring guest comfort
If Celbar is the chosen acoustic insulation
1. Fix the first layer of 12.5mm plasterboard with 25mm (1inch) drylining screws which will self-tap into the ‘C’ channel.
2. Do not position screws under the joists or the Iso-Mounts where they may make contact and form a path for sound transmission.
3. Keep the outer boards compressed into the Oscar Foam at the perimeter of the room. Keep gaps to the minimum and seal gaps with Oscar Seal. With the first layer of plasterboard installed and butting joints sealed, the ceiling is ready for the cutting of holes for the Celbar filling.
4. The holes of approximately 100mm (4 inches) dia to be cut in the ceiling board so hoses can be fed into the ceiling void. The cut out discs of plasterboard are retained to be replaced later after the Celbar fill. At least 1 hole between each joist, or more if required to ensure the void is full of Celbar. Where noggins split the void space in two, cut holes at either end of the void space. If unobstructed hoses can reach approximately 2.5 metres either side of the cut hole.
5. The ceiling is now ready for the installation of Celbar by Oscar Acoustics or a recommended installer.
6. With the hose pushed as for as it can go into the void a marker is put onto the hose so the operator can measure that he has fully filled the void or another hole is necessary.
7. The compacted bails are fed into a machine that breaks up the Celbar then blows it through the lightweight hose.
8. As the void completely fills, the air flow through the hose compresses the Celbar and the hose is pushed back by the compacting material. The operator feeds the hose back out of the hole and switches the Celbar delivery off at the appropriate point.
9. The last bit of material around the hole is then compacted by hand and the plasterboard cut-out is ready to be fixed back in position. N.B. The Celbar is compacted and does not fall out of the open hole.
NOTE: There is some mess with this operation but it is not hazardous and easily vacuum cleaned.
10. On completion of the Celbar fill, refit the 100mm dia cut blanks into the holes and use Oscar Seal to seal the disc cut-outs.
11. Apply the second layer of plasterboard, stagger the joints and compress the Oscar-Foam but do not allow the boards to make direct contact with the walls which will create a vibration path affecting the integrity of the soundproofing.
- Oscar Iso-Mount Assemblies
- 25x10x 10mtr rolls Oscar-Foam
(1x 3/8 inches x 32.8ft)
- Oscar-Seal Acoustic Sealant
- Celbar Acoustic Void Fill
Local builders merchants
- 12.5mm [1/2inch] Plasterboard
- 48mm Dry Lining Channel
- 60Kg/cu.mt mineral wool
Manufacturers include British Gypsum:
GypLiner type GL1 lining channel and GL3 Channel connectors.
N.B. GL8 wall support channel is not required.
Important Safety Warnings
- Mineral Wool and Celbar are also thermal insulators. Bring this to the attention of your qualified electrician who may have to allow for heavier cables to prevent cables overheating and ventilation gaps around downlighters etc.
- Fix cables securely and note the positions to avoid drilling into them later.
- Use a suitable detector to avoid cutting into electrical cables and water pipes.
- Consult the manufacturers of the plaster board for fixtures to be fixed directly to the plasterboard. Use fastenings as recommended by the plasterboard manufacturer.
- Locate the joists (various tools are available from DIY stores for this purpose) and ensure that all screws that are fixing the Iso-Mounts are fixed through the plasterboard and securely into the timber joists away from the joist edges. Do not fix to plasterboard alone, this will not support the weight and is likely to lead to a failure of the ceiling, with injury or worse.
- Only competent persons fully conversant with the use of Personal Protective Equipment should carry out the soundproofing ceiling installation.