Choosing Plasterboard Adhesives and Sealants for Effective Bonding

11th Jun 2024 -

For plasterboard bonding, the proper selection of adhesives and sealants achieves a seamless finish and ensures longevity. This guide breaks down all the essential elements to consider. We provide an overview of the adhesive and sealant options and the critical factors influencing their performance. By the end of this article, you will be better prepared to choose suitable products for your plasterboard projects. 

What are the drywall adhesive and sealant types?

A variety of adhesives and sealants are available, each designed for specific applications and performance requirements. From ready mixed plasterboard adhesive to joint compounds for sealing seams, choosing the right products ensures longevity and smooth finishes.

Plasterboard adhesives

Drywall construction adhesives

These are heavy-duty adhesives formulated specifically for bonding drywall to wood or metal framing. They provide an extremely strong permanent bond with high shear and tensile strength. 

Construction adhesives help eliminate nail or screw pops and cracking by reducing stresses on fasteners. Application is typically by a caulk gun along with framing members before drywall installation. 

Panel adhesives

Designed for laminating 2 drywall gypsum sheets together, panel adhesives create a high-strength bond that remains flexible. This allows curved or angled drywall designs without cracking the panels. 

Panel adhesives have good initial grab and form a permanent, long-lasting bond as they cure. They are applied with a caulk gun, trowel or in a bead form between the 2 drywall panels. 

Spray adhesives

Aerosol spray adhesives provide a quick-grabbing temporary bond when installing drywall panels. The adhesive sprays out in a thick, web-like mist that becomes tacky in seconds to form a bond. This allows you to position the drywall and make adjustments before the spray adhesive fully cures. 

Spray adhesives are very useful for tight spaces, small drywall repair areas or awkward framing designs where nailing is difficult. They do not provide a permanent bond and mechanical fasteners are still required.

Low-temperature adhesives

Low-temp drywall adhesives remain flexible and achieve a strong bond even when temperatures are below freezing. The adhesives have a lower minimum temperature rating, often around -12°C - -6°C (10-20°F), compared to standard construction adhesives. 

This prevents the need to warm up materials and construction areas in winter conditions. Low-temp adhesives bond drywall to framing securely until fasteners can be installed.

Plasterboard foam adhesive

Plasterboard adhesive foam comes in an aerosol foam that expands to secure panels in place without framing nails or screws. The foam adhesive is applied in a continuous bead along the framing. Drywall is pressed into it, allowing the adhesive to expand into the gap between panels and framing.

Foam adhesives add sound and thermal insulated plasterboard adhesive value. They provide a full-surface bond and help prevent fixing defects like nail pops. The rigid foam acts as a bonding and spacing material in one application.

Plasterboard sealants

Drywall joint compounds

Also known as mud or drywall compounds, this sealant for plasterboard is used for finishing drywall seams, corners, and fastener spots. Different types include topping compounds that provide a smooth finish coat over embedded tape on flat joints and corners. Lightweight joint compounds are less dense and easier to sand, making them ideal for final thin skim coats.

Setting-type compounds are set rather than air-drying for increased hardness and crack resistance. Quick-setting formulas allow faster recoating in a minimum of 90 minutes. Factors like dry time, shrinkage and sanding vary between different joint compound formulations. Proper application in multiple thin coats is essential for a seamless finished surface.

Acrylic latex sealants

These water-based sealants cure to form a durable, flexible seal on drywall surfaces. Key benefits include excellent adhesion to drywall facings as well as wood, concrete and metals. They are easy to apply, tool and clean up with water when wet. Many formulas allow painting once cured for an invisible seal.

Latex sealants provide a solid moisture and air barrier, yet remain flexible to prevent cracking. They offer good mildew resistance for bathroom/kitchen applications, are low in volatile organic compounds (VOCs) and are odourless. Latex sealants can be used for sealing drywall cutouts, joints, trim and gaps both before and after painting or finishing.

Silicone sealants

Silicone provides a heavy-duty, long-lasting flexible seal ideal for drywall joints with movement. It offers excellent elongation to span gaps and expansion/contraction. Silicone forms a weatherproof exterior seal able to resist UV, moisture and temperature extremes. It bonds firmly to drywall facings while remaining flexible without cracking or breaking adhesive bonds.

Silicone is available in different grades for construction, sanitary/anti-microbial, fire-rated assemblies etc. It is unaffected by moisture/humidity before or during curing. The durability and flexibility make it well-suited for plasterboard sealing joints in areas like windows, doors and high moisture areas.

Acoustical sealants

These sealants are formulated to block airborne sound transmission through drywall assemblies. They have a dense, non-hardening consistency that helps deaden noise and vibrations through drywall. Acoustic sealant provides a high sound transmission class (STC) rating. They must be applied to all drywall intersections, openings like outlets and penetrations.

Acoustical sealants remain flexible and non-drying to maintain the seal. They are easy to apply by caulking gun into gaps and seams. Some formulas also act as a smoke and fire barrier. Proper installation optimises the sound insulation and noise reduction performance of drywall partitions.

Intumescent sealants

Intumescent sealants expand with heat to create a porous layer that seals gaps and prevents the spread of fire. They are ideal for sealing penetrations, joints and openings in fire-rated drywall assemblies. This allows drywall partitions to maintain their approximate 1-hour fire rating by sealing off potential paths for fire. 

Intumescent sealants are available in different grades based on fire rating requirements. Proper installation depth and detailing are crucial for these sealants to work as intended.

Butyl sealants

Butyl-based sealants offer excellent flexibility, high elasticity and resistance to ageing. The rubbery consistency allows them to stretch and return to shape with joint movement. Butyl adheres tenaciously to drywall, concrete wood and other common building materials.

It provides a long-lasting, weatherproof seal, making it suitable to seal plasterboard joints and seams that experience temperature fluctuations. Butyl has good chemical resistance but can be difficult to tool and clean up.

Polyurethane sealants

Moisture-cured polyurethane is a durable and abrasion-resistant type of drywall sealant. It forms a tough, waterproof and flexible seal that will not shrink or crack with movement. Polyurethane adheres to various substrates like drywall, wood, concrete, glass and plastics.

It is well-suited for high-moisture areas like bathrooms, kitchens and exterior drywall joints. Polyurethane provides good chemical and mould/mildew resistance. Many are paintable but may require a plasterboard primer.

Elastomeric sealants

These high-performance sealants stretch up to 500% of their original size and recover fully without compromising adhesion. This extreme flexibility allows them to withstand high joint movement in drywall applications. 

Elastomeric sealants maintain a durable, weatherproof, UV-resistant seal on both interior and exterior joints. They create a tough yet rubbery bond that absorbs expansion, contraction, vibration and deflection. Elastomeric sealants span cracks up to 50mm (2 inches) wide while remaining bonded.

What is the dot and dab plasterboard adhesive method?

The dot and dab technique is a specialised method for installing plasterboard directly to solid wall or ceiling substrates. Rather than conventional framing, the drywall dot and dab system relies on an adhesive to securely bond the panels.

Surface preparation

Proper substrate preparation is important for successful dot and dab installations. The surface must be clean, dry and free of any contaminants that could hinder adhesion. Concrete, masonry and drywall surfaces typically require priming or sealing first. 

Adhesive application

The adhesive is placed onto the substrate in 1 of 2 patterns. The first are thick dots that are spaced evenly every 150mm - 400mm (6-16 inches) across the substrate. Dabs of adhesive are then placed in vertical lines spaced in a similar pattern. 

Panel bonding

Immediately after applying the adhesive pattern, the drywall panel is firmly pressed into the dots/dabs. This forces the adhesive to spread and transfer to both surfaces, forming a permanent durable bond. 

Adhesive curing

Plasterboard adhesives develop an initial grab or tack within 30-60 minutes to temporarily hold the drywall in place. Full cure times for creating the permanent flex-resistant bond may take 24-72 hours depending on temperature/humidity conditions.

Can you dot and dab all plasterboard adhesives?

Not all plasterboard adhesive types are suitable or recommended for the dot and dab technique. Suitable types are typically elastomeric polymers or polyurethane-based formulas with the following characteristics.

• High initial green strength (early bonding) to support drywall weight.
• Ability to bond to multiple substrates like concrete and drywall.
• Permanent flexibility to prevent cracking from substrate movement.
• Excellent shear and tensile strength for load-bearing assemblies.
• Quick-setting or fast-curing properties.
• Compliance with building standards for dot and dab installations.

Using standard drywall construction adhesives, panel adhesives or general-purpose sealants for dot and dab is not advisable. While they may work initially, these products typically lack the essential performance properties.

• Insufficient green strength to support panels until cured.
• Limited flexibility leads to bond failure from movement.
• Inadequate shear and tensile strength for drywall loads.

Spray adhesives are also unsuitable as they only provide temporary tack and bonding properties before disbanding.

How much plasterboard adhesive and sealant do you need?

Using the right amount of adhesive or sealant ensures proper bonding, sealing and longevity in drywall installations. Too little compromises performance, while excessive overuse is wasteful and can create other issues. There are general best practices to follow.

Plasterboard adhesives 

Drywall construction adhesives

• For bonding to framing: Apply ½-inch beads every 6-8 inches or ¼-inch beads every 4 inches along framing members.
• Dot and dab method: ⅜-inch thick dots/dabs spaced 6-16 inches apart covering 25-50% of the drywall surface.

Panel adhesives

• ¼-inch thick continuous beads along the plasterboard edges.
• For laminating 2 drywall sheets: Apply parallel ¼-inch beads every 6-8 inches over one panel before joining.

Spray adhesives

• Apply a web-pattern mist covering 60-80% of the substrate surface for a temporary tack. 

Low-temperature adhesives

• Same coverage as standard construction adhesives (½-inch beads every 6-8 inches or ¼-inch beads every 4 inches).

Foam plasterboard adhesives

• Apply ½ - ¾-inch thick continuous beads every 12-24 inches along the framing or substrate.
• Beads should cover 25% of the overall surface area.

Plasterboard sealants 

Joint compounds

• For taping drywall seams: Apply a thin coat over embedded tape.
• For finish coats: Feather out about 6-10 inches from each side of the joint for seamless finishing.

Acrylic/silicone/acoustical sealants

• When sealing gaps and joints: Apply a continuous bead to fill voids for an air/moisture-tight seal.
• For fire-rated assemblies: Follow specific fill requirements for joint depth to maintain rating.

Intumescent sealants

• Apply a minimum ⅝-inch depth of sealant in all drywall penetrations and openings for fire protection.

Butyl sealants

• For joints: Apply a ¼-inch minimum depth bead to allow for expansion.
• Drywall seams: Apply a ½-inch bead before embedding joint tape.

Polyurethane sealants

• Gaps/joints: Use a minimum ¼-inch bead depth.
• Drywall penetrations: Apply a ⅜-inch minimum depth sealant.

Elastomeric sealants

• Expansion/movement joints: Install a minimum ½-inch depth bead.
• Panel joints/seams: Apply ⅜ - ½-inch bead before embedding tape.

Does plasterboard thickness affect adhesive bonding?

The thickness of plasterboard panels potentially impacts the adhesive bonding performance in certain installation scenarios. Manufacturers provide recommendations suitable for standard ½-inch or ⅝-inch thick boards. However, thinner or thicker panel types may require adjustments.

Thinner drywall panels (¼-inch)

When bonding thin, lightweight ¼-inch drywall panels, there are a few considerations.

Adhesive application - Applying excessive adhesive may overload the panel's strength and cause deformation or buckling under the weight. Using the minimum recommended bead size and spacing is advisable.

Curing time - Thinner drywall allows adhesives to cure faster from both sides. Following minimum cure times before joint finishing is important to prevent delamination.

Lamination uses - Thinner board panels are sometimes laminated in layers. Panel adhesives capable of bonding the facings without excessive bleed-through are required.

Heavier drywall panels (⅝-inch or greater)

Extra heavy-duty adhesives may be necessary for bonding thicker, denser drywall types such as the following.

Fire rated panels - These use specialised fire-resistant cores and facings, often requiring a high-strength structural adhesive application.

Moisture resistant panels - Increased panel weight from water resistant cores demands maximum sheer and tensile adhesive strength.

Structural panels - Used as exterior sheathing, these enhanced panels need maximum adhesive bonding capabilities.