For doors
Soundproofing and acoustic treatment for doors
A door is the only part of a wall that has a gap built into it on purpose, and it is the lightest part of the wall as well. A room performs like its door, not like its partition, so the threshold gap under the leaf is normally the single biggest leak in the room and the cheapest thing in the whole job to close.
- Perimeter seal
- EPDM 6 x 6 mm D-type, 18 ft roll
- Bottom seal
- Silicone, 920 x 15 mm, doors to 3 ft
- Leaf mass
- SoundBlanket® MLV, STC 34 at 4 mm
- Quote
- Within 48 hours, from leaf size and gaps
Send the leaf size, whether the leaf is solid or hollow, the frame material, and the gap at the head, the two stiles and the floor. We manufacture and supply the seals and the mass layer; we do not make doorsets, and we do not carry out on site consultancy, measurement or installation.
01 / What actually goes wrong
Three faults, and they are not equally expensive to fix
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The gap under the leaf
Almost every door is hung with an undercut so it clears the floor finish, and that undercut runs the full width of the opening. Airborne sound passes through an opening far more freely than through any panel, so a continuous slot at the threshold carries more energy than the rest of the door does. It is also the one gap that nobody sees, because a closed door looks closed. Fix this before anything else on the door and before anything at all on the wall.
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The perimeter, and what people seal it with
The head and the two stiles need a compressible seal that the leaf closes onto. Open cell foam strip from a hardware shop does this for one season: it takes a compression set, flattens, and the gap is back without anyone noticing. EPDM holds its compression set through heat, cold and UV, which is why it stays effective and why it is what we supply.
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A hollow leaf
A standard flush door is two thin skins over a honeycomb or a light frame. It weighs almost nothing, so it blocks almost nothing, and its skins drum with any low frequency energy in the room. Perfect seals on a hollow leaf still leave you with a lightweight panel in the middle of the wall. The leaf has to gain mass, either by adding it or by replacing the door.
02 / The build-up
Close the gap, close the threshold, then add the mass
In that order. The seals are inexpensive and give the biggest change; the mass layer is worth adding once the openings are closed, and worth very little before that.
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Layer 1
EPDM perimeter seal, head and both stiles
A D-profile seal applied to the rebate so that the closing leaf compresses it along the head and both stiles. It is self-adhesive, cuts with scissors, and bonds to metal, timber and glass frames, so it goes on an existing door without taking it off its hinges. Run it in one continuous length per side and butt the corners; a break at a corner is a hole.
6 x 6 mm D-type, 18 ft per roll, and the section splits into two seals from one roll. Also supplied in silicone through door and window seals.
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Layer 2
The threshold: bottom seal or drop-down seal
The bottom of the leaf gets its own seal, because the perimeter seal cannot reach it. A silicone bottom seal fixed to the face of the leaf sweeps the floor and closes the undercut. Where the floor finish changes through the opening, or where the leaf has to clear a carpet, a drop-down seal that retracts as the door opens is the better fit. This is the layer that changes a room the most for the least money.
Silicone bottom seal 920 x 15 mm, for doors up to 3 ft wide. Bottom and drop-down seals are listed under door and window seals.
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Layer 3
Mass and damping on the leaf
SoundBlanket® bonded to the face of the leaf, or laid into the core when a door is being made, turns a light panel into a dense one. Because it is limp rather than stiff it adds weight without making the leaf ring. Add BassBloc® behind a face panel where the leaf is drumming with low frequency energy from an AV room or a plant space. Check the hinges and the closer will still take the added weight, and re-check the gaps afterwards, because a thicker leaf changes them.
STC 30 at 2.5 mm, STC 34 at 4 mm, to ASTM E90. 2100 kg/m³. Class A surface burning to ASTM E84. Custom 1 to 10 mm. BassBloc® NRC 0.85 at 20 mm, to ASTM C423.
What each part of the opening needs
| Part of the opening | What goes there | Why |
|---|---|---|
| Threshold | Silicone bottom seal, 920 x 15 mm, or a drop-down seal | The largest continuous opening in the door, and the first thing to close |
| Head and stiles | EPDM 6 x 6 mm D-type in the rebate, continuous per side | Holds its compression set, so the seal is still a seal in a year |
| The leaf | SoundBlanket® 2.5 or 4 mm on the face or in the core | A hollow leaf blocks very little whatever the seals do |
| A drumming leaf | BassBloc® 20 mm behind a face panel, never exposed | Damps panel resonance from AV rooms and plant spaces |
| Glazed doors and openings | Soundproof curtain, STC 30, 10 to 12 mm | Where the leaf cannot be changed, or the opening has no leaf at all |
| Reflections at the door wall | PET felt panels, NRC 0.30 at 9 mm to 0.60 at 24 mm | A different job: how the room sounds, not what leaves it |
These are product figures. A door rating is a property of a complete doorset, leaf, frame, seals and ironmongery tested together, which is not something we manufacture or certify. Where a rated doorset is specified, an acoustic consultant should set the requirement.
03 / Sizes and fitting
How to measure a door before you order
Four measurements and one look at the leaf. Send us these and we can quote the seal set and the mass layer without seeing the door.
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Where a solid leaf is not optional
Studio, theatre and AV entrances, plant room doors and rooms that need real speech privacy are the cases where sealing an existing hollow door is not enough. The leaf has to be dense to begin with, usually a solid core door built by a joiner or supplied as a doorset, and a lobby with two doors and a gap between them beats one very good door.
- SoundBlanket® laid into the core at the time the leaf is made
- HDHMR boards, 8 to 24 mm, as the dense facing for a made-up leaf, FR grade on request
- EPDM perimeter seal plus a drop-down threshold seal on both leaves of a lobby
- BassBloc® 20 mm and PET felt lining the lobby between the two doors
The five things to send us
| Measure | How | What it decides |
|---|---|---|
| Leaf width and height | The leaf itself, not the opening. A standard bottom seal covers doors up to 3 ft wide | Whether one 920 mm bottom seal fits, or the seal has to be made longer |
| Perimeter run | Height, plus height, plus width, in feet. One 18 ft roll splits into two seals | How many rolls of EPDM the door needs |
| Threshold gap | Slide a steel rule under the closed leaf at both ends and the middle | Bottom seal or drop-down seal, and whether the floor is level |
| Frame rebate | The flat face the leaf closes against, and whether it is timber, metal or glass | Where the D-profile goes and whether the self-adhesive will hold |
| Leaf type | Knock on it. A hollow leaf sounds like a drum and feels light to swing | Whether mass is worth adding to this leaf or the leaf should be replaced |
- FIT ORDER
Seals first, then the mass layer, then re-check the gaps. Adding thickness to the leaf changes every clearance you measured.
- BONDING
EPDM arrives with the adhesive tape already applied. For SoundBlanket® on a leaf, use SR adhesive at about 20 ml per sq ft.
- DISPATCH
SoundBlanket® in 2 to 5 days within India and 7 to 10 days for export. PET felt panels in 3 to 7 days.
04 / What we see go wrong
Five door mistakes that undo the wall
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Sealing three sides out of four
The head and stiles get a seal, the threshold is left as it was, and the result barely moves. The undercut is the biggest opening of the four and it is the one people leave.
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Foam strip instead of EPDM
It works for a few months, then flattens and crumbles and the gap comes back. Nobody re-checks a door that was already fixed once.
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Mass on the leaf, gaps still open
Weight added to a door that still has a slot under it. Sound goes round the mass through the opening, so the leaf is now heavy, the hinges are working harder, and the room is the same.
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A hollow leaf in a room built to be quiet
The partition is specified properly, the door is whatever the contractor's standard is, and the assembly performs like the door. The door should be specified with the wall.
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Foam panels stuck to the door face
Absorption on the door changes how the room sounds and does nothing to what passes through it. Two different problems, two different products.
05 / Specifications
Tested performance, with the standard it was measured to
| Product | Tested performance | Test standard |
|---|---|---|
| SoundBlanket mass loaded vinyl | STC 30 at 2.5 mm, STC 34 at 4 mm; 2100 kg/m³ | ASTM E90 |
| BassBloc low-frequency absorber | NRC 0.85 at 20 mm, 0.95 at 40 mm; 100 kg/m³ | ASTM C423 |
Test reports are issued with project supply. NRC and STC are the figures we publish and stand behind; anything beyond those two is the scope of an acoustic consultant. The full set of reports is listed on the certifications page.
06 / How we can help
What we do, and what we do not
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We do
- Manufacture SoundBlanket®, BassBloc® and the seal range at the Palwal plant, Haryana
- Quote a seal set and a mass layer from the leaf size and the four gaps, usually within 48 hours
- Supply test reports, technical data sheets and specification text
- Cut SoundBlanket® and panel material to leaf size for a door being made up
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We do not
- Manufacture doorsets, or certify a leaf, frame and ironmongery as a rated assembly
- Carry out on site acoustic consultancy or measurement
- Install. We manufacture and supply the components
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We refer
We work with associated acoustic consultants and installers across India and can put you in touch with them for design verification or execution. Ask when you send the door details.
Questions