This guide covers the main types of construction adhesive, where each one is used, and some practical tips that make a real difference.
Why Adhesive?
The main advantages of adhesive over mechanical fixings:
- No fixing points visible on the surface particularly valuable in finish joinery and decorative work
- Distributed load adhesive spreads load across the full bonded area rather than concentrating it at fixing points, which is stronger in many situations
- Vibration resistance a bonded joint doesn't loosen over time in the way screws can
- Filling minor gaps gap-filling adhesives compensate for imperfect surfaces
- Multi-material bonding some adhesives bond materials that can't be mechanically fixed (fixing trim to masonry without drilling, for example)
The limitation is that adhesive is permanent or very difficult to reverse, and bond strength depends on correct surface preparation and application.
PVA (Polyvinyl Acetate)
PVA is the traditional woodworking glue the white or slightly yellow liquid that comes in a bottle. It bonds porous materials: timber to timber, timber to plywood, MDF to MDF.
Strengths: Strong timber-to-timber bond, inexpensive, easy to apply and clean up with water before curing, sandable once dry.
Limitations: Not waterproof in standard formulation. For external use, use exterior-grade PVA (often marketed as D3 or D4 rated). Also not suitable for bonding non-porous surfaces it relies on penetrating the material slightly to form a grip.
Where it's used: Cabinet making, furniture assembly, timber joinery, laminating timber, filling gaps in timber before finishing.
Tips: Apply to both surfaces, allow a minute for the glue to become tacky (depending on the product), then clamp firmly until cured. Too little clamping pressure produces a weak joint. Excess PVA squeezes out at the joint line wipe off before it dries for a clean finish.
Construction Grab Adhesive (No-More-Nails Type)
Grab adhesives sold under brand names like No More Nails, CT1, Gorilla Grab, and Stixall are solvent or polymer-based adhesives designed for bonding construction materials without mechanical fixings.
Strengths: Bonds a huge range of materials wood, plasterboard, concrete, brick, metal, ceramic, plastic, foam. Most are gap-filling. Many are flexible when cured, so they accommodate slight movement in the joint.
Limitations: Lower immediate grab than their marketing often implies most need either temporary support or mechanical fixings to hold the joint while curing. Bond strength varies enormously between products.
Where they're used: Fitting skirting board, architrave, coving, timber battens, fixing plasterboard to masonry (as an alternative to traditional dot-and-dab), mirror and panel bonding.
Tips: Surface must be clean, dry, and free of dust. Apply in blobs or a zigzag bead, not a continuous line this allows the adhesive to compress and spread when the surfaces are pushed together. Temporary pins or fixings are often needed while the adhesive cures.
Silicone Sealant
Technically a sealant rather than a structural adhesive, but silicone is used as an adhesive in many construction applications particularly where flexibility and water resistance are needed.
Where it's used: Sealing around baths, showers, and sinks; sealing window and door frames; bonding glass; movement joints between different materials.
Types: Standard (for general use), sanitary grade (mould-resistant for kitchens and bathrooms), neutral cure (for sensitive metals like copper and lead), and fire-rated (for penetrations through fire-rated walls and floors).
Tips: Surface must be completely dry and grease-free. Silicone doesn't bond to dusty or contaminated surfaces. Apply in a single bead and tool smooth with a wet finger immediately it starts to skin quickly. Old silicone must be fully removed before reapplication new silicone doesn't bond well to old silicone.
Epoxy Adhesives
Two-part epoxy consists of a resin and a hardener that are mixed together and create a chemical bond when they react. This produces one of the strongest bonds available in construction.
Strengths: Very high strength, excellent adhesion to metals, ceramics, concrete, and glass. Resistant to water, chemicals, and temperature variation once cured.
Limitations: More expensive than other adhesives, requires careful mixing in the right ratio, and has a limited working time (pot life) once mixed. Some formulations are brittle when cured and don't handle movement well.
Where they're used: Structural repairs to masonry and concrete, bonding metal fittings, chemical anchor systems for concrete fixings (the resin in chemical anchors is typically epoxy or polyester based).
Polyurethane Adhesive (PU Adhesive)
Polyurethane adhesive is a flexible, moisture-curing adhesive that foams slightly as it cures, filling small gaps.
Strengths: Bonds timber, concrete, brick, metal, and most plastics. Flexible when cured, so handles movement and vibration well. Waterproof.
Limitations: Expands as it cures apply less than you think you need. Difficult to remove once cured (mechanical methods only). Stains skin and clothing and is difficult to remove before curing.
Where they're used: Structural timber bonding, boat building, outdoor furniture, and any application needing a waterproof flexible bond.
A Quick Reference
| Adhesive Type | Best For | Waterproof? | Flexible? |
| PVA (interior grade) | Timber to timber | No | No |
| PVA (exterior D3/D4) | External timber joinery | Yes | No |
| Grab adhesive | Multi-material bonding, trim, battens | Yes (most) | Yes (most) |
| Silicone sealant | Sealing, wet areas, glass | Yes | Yes |
| Epoxy | High-strength structural bonds, metal | Yes | No |
| Polyurethane | Structural timber, outdoor use | Yes | Yes |
In practice, adhesive and mechanical fixings are often used together the adhesive adds bond strength and rigidity, the fixings hold everything in place while the adhesive cures and provide additional security. This combination approach is stronger than either method alone for most applications.