D3 PVA Adhesive

What is D3 PVA, and which Selleys glue meets it?

Your floating floor instructions specify D3 PVA. The 'D' rating relates to the moisture resistance or durability of the glue, and D3 generally describes cross-linking exterior-grade PVA glues with good weather and water resistance — though not waterproof. These are the glues sometimes described as "yellow glues", and they are much more water resistant than standard interior-grade PVAs.

Selleys Aquadhere Exterior PVA Glue is a D3 cross-linking PVA glue. That is the product in the Selleys range that answers your flooring manufacturer's requirement.

Why a floating floor asks for D3

A floating floor is not fixed to the subfloor. It is a raft of boards held together only by their own joints, and the glue in those joints is all that stops the floor opening up. That places two demands on the adhesive that an ordinary interior PVA is not designed to meet.

Moisture, from above and below. Floors get mopped, spilled on, and — in the case of a slab — exposed to residual moisture from underneath. A standard interior PVA is not water resistant and softens with moisture. A cross-linked PVA is a different chemistry: the cross-linking reaction gives a cured film that resists water rather than re-softening in it.

Constant, low-level movement. A floating floor moves seasonally as the room's humidity changes. The joints work slightly, every year, forever. The D-rating system exists precisely to distinguish glues that survive that from glues that do not.

The word to hold on to is resistant, not waterproof. D3 means good weather and water resistance; it does not mean the floor can be flooded. Aquadhere Exterior's own data sheet states it is not suitable for below waterline applications or continuous submersion.

Aquadhere Exterior specifications

Property	Typical result
Technology	Industrial-grade polyaliphatic cross-linking PVA
Colour	Off-white, dries clear with a yellow tinge
Coverage	Approximately 5 m²/L
Viscosity	2000–3500 cP
pH	2–3
Clamp time	30 minutes softwoods; 1 hour hardwoods
Maximum bond time	24 hours
Packaging	250 mL, 500 mL, 1 L and 4 L bottles

Indicative data only, not intended for the preparation of specifications.

What the numbers mean when laying a floor

Coverage of about 5 m² per litre is a bonding figure, not a flooring figure. On a floating floor you are running a fine bead in a tongue-and-groove profile rather than coating a face, so a litre goes a very long way — but check the flooring manufacturer's own stated consumption, because they know their profile.

Maximum strength at 24 hours sets when the floor can be used. The joints are not at full strength on the day they are laid. Keep foot traffic light and do not move heavy furniture back in until the following day, and allow longer in cold or damp conditions.

The pH of 2 to 3 is worth knowing if there is metal about. This is an acidic adhesive, which is part of why the data sheet is so firm about iron contamination: Aquadhere will stain brown or black if contaminated with rust, or in the presence of tannins in many woods.

How to use it on a floating floor

1. Follow the flooring manufacturer's instructions first. They specify the glue rating, the bead position in the profile, the expansion gaps and the acclimatisation period, and none of that is Selleys' to override.
2. Make sure the surfaces to be bonded are close fitting, dry and clean.
3. Shake the bottle before use.
4. Apply the adhesive to one surface only, in the position the flooring maker specifies — usually the upper wall of the groove.
5. Close the joint and tap it up tight. Keep the boards under pressure while the glue sets; on a floating floor, straps or wedges against the wall do the job of clamps.
6. Wipe off excess adhesive with a damp cloth while it is still wet. Squeeze-out on a factory-finished board surface is far easier to remove now than later.
7. Do not stress the joints for 24 hours. Maximum strength is attained in 24 hours, longer in cold, damp conditions or with dense timbers.

Limitations

• Not waterproof. D3 means good weather and water resistance, not waterproof. Not suitable for below waterline applications or continuous submersion.
• Not recommended for joints subjected to constant high stress.
• Avoid contaminating with iron and steel. Rust contamination, or tannins in many woods, will stain the glue brown or black.
• Suitable for exterior use in non-structural applications only.
• Cured product can only be sanded or scraped off — a problem on a pre-finished floor surface, so wipe while wet.

If your floor needs something else

Some engineered and timber floors are glued down to the subfloor rather than floated, and that is a different product entirely. Selleys makes dedicated flooring adhesives for that method, including Timberflex Timber Flooring Adhesive, along with subfloor preparation products such as VBS Vapour Barrier and SLC50 Leveller. If your instructions ask for a moisture barrier or a levelling compound before laying, do not skip it — a floating floor over a damp or uneven slab fails regardless of which glue is in the joints.

Safety: the glue is the clean part of this job

An unusual thing about this answer is that the recommended product is the benign one. Aquadhere Exterior is not classified as hazardous under the criteria of Safe Work Australia GHS 7 — no signal word, no hazard statements — and its own safety data sheet says so definitively rather than leaving a gap. For a product you will be wiping off boards with a damp cloth all day, kneeling on the floor beside it, that is worth knowing. Its pH of 2 to 3 is the reason for the iron-staining warning above rather than a health classification.

The subfloor preparation is where the hazards are. If your instructions call for levelling before you lay, SLC50 Leveller carries the signal word Danger on four classifications, and the first one is the serious one:

• H350 — may cause cancer (Carcinogenicity, Category 1). Say plainly what this is: may cause, not suspected of causing. The exposure is respirable crystalline silica in the dry powder, at bag-opening and while the paddle mixer is running. The cured, levelled slab is not the hazard.
• H318 — causes serious eye damage (Category 1). Permanent, not a sting. The wet compound is alkaline and cementitious, and alkali eye injuries keep penetrating rather than self-limiting.
• H315 causes skin irritation, and H335 may cause respiratory irritation.

Both of the Category 1 hazards map onto one posture: crouched over a mixing bucket on the floor of a closed, empty room. That is where the dust concentration is highest, and it is where your eyes are lowest and closest to a splash. Cut the bag low into the bucket rather than tipping it from height, mix with the doors and windows open or outside altogether, wear a P2 respirator for the mixing and eye protection for the pour, and do not sweep the dry spill — sweeping puts the respirable fraction straight back into the air.

If you end up using a polyurethane rather than a PVA, Aquadhere Durabond is the most heavily classified adhesive in the range: H334, may cause allergy or asthma symptoms or breathing difficulties if inhaled (Category 1A); H351, suspected of causing cancer; and H373, may cause damage to organs through prolonged or repeated exposure, alongside H332, H317, H335, H315 and H319. H334 is the one to weigh on a flooring job, because respiratory sensitisation is generally permanent once acquired and it is built by long, enclosed, repeated exposure — and a floor is hours of work in a closed room. For a floating floor that specifies D3, Aquadhere Exterior meets the requirement and carries none of that.

Poisons Information Centre — 131 126 in Australia, 0800 764 766 in New Zealand.

Common questions about D3 PVA

What does D3 mean?

The 'D' rating relates to the moisture resistance or durability of the glue. D3 generally describes cross-linking exterior-grade PVA glues with good weather and water resistance.

Which Selleys glue is D3?

Selleys Aquadhere Exterior PVA Glue is a D3 cross-linking PVA glue.

Is D3 waterproof?

No. D3 means good weather and water resistance, not waterproof. Aquadhere Exterior is not suitable for continuous submersion or below waterline use.

Is D3 the same as a yellow glue?

Cross-linked PVAs are sometimes described as yellow glues, and they are much more water resistant than standard interior grade PVAs.

Can I use Aquadhere Interior instead?

Not if your flooring manufacturer specifies D3. Aquadhere Interior is not waterproof and is intended for interior work where moisture exposure is minimal.

How much glue will I need?

Coverage is approximately 5 m² per litre for surface bonding. On a tongue-and-groove profile you will use far less; check the flooring maker's figure.

How long before I can walk on the floor?

Maximum bond strength is attained in 24 hours, longer in cold or damp conditions. Keep traffic light until then.

How do I clean up squeeze-out?

Water, while it is still wet. Cured glue has to be sanded or scraped, which will mark a pre-finished board.

Does it stain the timber?

It will stain brown or black if contaminated with rust or in the presence of tannins in many woods. For tannin-rich timbers, Selleys recommends a polyurethane such as Aquadhere Durabond instead.

What if my floor is glued down rather than floating?

That is a different adhesive class. See the flooring range for direct-stick timber flooring adhesives and subfloor preparation products.