Plywood Interior - Two and a Half Storey House - Bradley Van Der Straeten - Photography by French and Tye
Plywood has been a favourite with architects since the start of the modern movement in the late 1920s, when its potential as a design material was first explored. It continues to feature prominently in many architect-designed homes built today.
Extremely strong, attractive and environmentally sustainable, plywood is highly suitable for a range of interior applications.
Here, we look at what plywood actually is; the types best suited for interior uses; grades, sizes and associated costs; and practical advice on how plywood should be installed and finished.
A brief history of plywood in design
Plywood kitchens and storage units
What is plywood?
Plywood is a manufactured wood-based panel product consisting of timber veneers glued together, layer by layer, under high heat and pressure. The grain of each veneer is orientated perpendicular to the next, giving the panel strength and rigidity. Manufactured from a wide variety of timber species, it ranges from sheets formed in thin layers of slow-grown hardwoods to thicker layers of fast-growing softwoods.
A standard plywood sheet measures 2440 x 1220mm and comes in a range of thicknesses, with larger sizes also available. Plywood is graded according to the quality of its facing veneers, which are typically a higher grade than the layers within.
A Brief History of Plywood in Design
Plywood has been around since the time of the ancient Egyptians. The modern plywood panels we are familiar with today, however, were first manufactured in the mid nineteenth century following innovations in timber technology during the industrial revolution.
Plywood featured in the manufacture of furniture during the 1850s but for the most part is was used for making packing cases.
Modernist architects of the 1930s soon began to see plywood’s potential as a design material and began to experiment with techniques to create new organic forms. The Palmio Chair, designed in 1931-32 by Finnish husband and wife architects Alvar and Aino Aalto is an exemplar in bent wood manufacturing and continues to be admired for its sculptural form and comfort to this day.
Palmio Chair by Alvar Aalto - 1931-32
By the 1940s another husband and wife architect duo, Charles and Ray Eames in the USA, developed new moulding methods that allowed them to produce complex curved three-dimensional forms. The Eames DCM (dining chair metal), designed in 1945, was one of the most influential chairs of the twentieth century and has been copied and revised endlessly by designers and manufacturer’s all over the world since its production – see IKEA! Other notable works include the iconic Eames Lounge Chair and Ottoman, designed 1953-55.
DCM Chair by Charles Eames for Herman Miller - 1945
Sale House - Richard Neutra - 1960 - Photographer Cameron Carothers
The mid century modern houses of the 1950s and 60s saw the introduction of plywood lined interiors and bespoke joinery as a means to provide warmth and character and zone open plan spaces. Richard Neutra’s Sale Residence, constructed in 1960, is an excellent example.
Plywood continues to feature in many architect-designed homes built today and, being a sheet material, is perfectly suited to the new digital age. Computer Numerical Control (CNC) production allows plywood parts to be cut and routed with extreme accuracy, opening up a whole range of design possibilities. CNC cutting is currently being utilised by architects to make a whole range of different objects ranging from furniture, kitchens/ built in joinery and prefabricated housing – see video below by WikiHouse.
Plywood Interior - Pottery Shed - Grey Griffiths - Photography by Adam Scott
Plywood interior uses
Plywood is a highly versatile material that can be used in a range of interior applications, including:
Plywood comes in a range of types, grades and sizes and can be fixed and finished in a variety of different ways.
Types of plywood
When selecting the best type of plywood for interior uses, a range of factors need to be considered: strength, weight, durability, stability, appearance and environmental sustainability.
Nordic plywood
Nordic plywood, sometimes referred to as Baltic plywood, is the main supply of quality plywood in the UK. Produced mainly in Finland and Latvia from sustainably grown birch or spruce, it is an extremely versatile building material and well suited to wide range of interior applications.
Birch plywood is typically formed in 1.4mm thick all-birch veneers and has an attractive, close-grained finished surface, making it a popular choice for furniture and interior uses. Birch plywood is uniform and dimensionally stable, which allows it to be cut with great precision without risk of degrading.
Spruce plywood is usually formed in thicker 2.6 or 3.2mm veneer layers. It is much lighter than birch plywood but equally strong and rigid. Its characterful knotted appearance is an acquired taste, but spruce plywood is perfectly suited to interior applications. Spruce is widely used in the production of Cross Laminated Timber (CLT) panels- effectively beefed-up plywood - to make structural and prefabricated building components.
Nordic plywood is exceptionally strong and rigid, possesses excellent acoustic properties and can help create a healthy indoor environment due to its ability to balance temperature and humidity variations.
Nordic birch is non-toxic as the layers are bonded together with exterior quality phenol-formaldehyde resin adhesives giving it a class E1 formaldehyde rating (i.e. very low release). The adhesive appears as contrasting dark, purple-brown glue lines against the lighter veneers, and is regularly incorporated into designs.
All Nordic plywood carries PEFC certification and is one of the most environmentally friendly building materials available today.
Birch Plywood Storage - Two and a Half Storey House - Bradley Van Der Straeten - Photographer French+Tye
Spruce Plywood Interior - Gallery House - Studio Octopi - Photography by Julian Lanoo
Laminated plywood
Plywood can be finished with High Pressure Laminate (HPL) or melamine.
HPL consists of multiple layers of resin-impregnated kraft paper bonded together underheat and high pressure to form a high-density finish. Adhered to plywood, it creates an extremely durable finish and is a great choice for interior items that require frequent cleaning, such as kitchen worktops and cabinetry.
Melamine is a low-pressure laminate consisting of a single latter of melamine paper bonded directly to the substrate. Melamine plywood is not as robust as HPL and is therefore more suited to lower impact areas.
Laminated birch sheets are available in a range of colours from large timber merchants such as James Latham. Alternatively, joinery workshops can apply laminates to the plywood of your choosing.
HPL Kitchen Doors
Ash Veneer Interior - Grove Park - O'Sullivan Skoufoglou - Photography by Stale Eriksen
Real wood veneered plywood
In addition to laminates, real wood veneers can be adhered to plywood, offering further interior options. Typically 0.6mm thick (1mm, 1.5mm and 2mm are also available), veneers are adhered to both faces of the plywood to prevent the sheet from warping. Sustainable options include ash, oak, beech and Douglas fir.
The appearance of real wood veneered plywood is not only determined by the timber species, but also the way the facing veneer is sliced and joined together. This offers the designer a huge variety of options.
Slicing options include (non exhaustive):
Jointing methods included (non exhaustive):
Many architects look to express the true character of plywood by incorporating exposed raw edges into their designs. However, real wood veneer strips (and solid trims) can be applied to conceal the edges, if desired.
Fire retardant plywood
In areas at increased risk of fire, fire retardant plywood may be needed to meet building regulations. Fire protective coatings can be applied to standard plywood boards to improve performance; however, a manufactured board - where all veneers are soaked in a fire-retardant solution - offers the best protection. Retardant coatings can darken the facing veneer which is not always aesthetically desirable. A pre-manufactured board provides a controllable finish.
Garnica Fireshield, consisting entirely of sustainably managed poplar, is a firm favourite with architects as it not only provides excellent fire resistance but also a pale, high-quality finished surface onto which standard finishes can be applied.
Other options include Hanson Fire Retardant Birch Plywood and WISA Spruce FR.
Read on for more information on how to finish plywood.
Plywood grades
Most types of plywood are graded according to the quality of the facing veneers. In the UK, birch plywood is graded as follows (non-exhaustive):
Birch Ply sheets and Plug Mark
Spruce plywood is graded as follows:
Nordic plywood carries PEFC certification and is one of the most environmentally friendly building materials available today.
Plywood sizes
Plywood is typically manufactured in 1220mm x 2440mm sheets, although larger 1220mm x 3050/3660mm and1525mm x 3050mm sheets are available.
Standard sheet thicknesses include 4mm, 6mm, 9mm, 12mm, 15mm,18mm, 21mm, 24mm and 27mm. Larger thicknesses of up to 50mm are available from specialist suppliers.
Plywood costs
The cost of plywood is dependent on species, grade, thickness and quantity.
At the time of writing, a single sheet of 1220 x 2440 x 12mm Grade BB/BB birch plywood costs about £100. The same sized sheet in premium Grade S/BB costs about 35% more.
A standard sheet of 1220 x 2440 x 12mm Grade 11/111 Wisa-spruce plywood costs about £50.
12mm Garnica Fireshield is about £125 per sheet.
18mm melamine birch plywood costs approximately £180 per sheet.
18mm HPL birch plywood costs about £300 per sheet.
A single sheet of 18mm birch plywood veneered in white ash or European oak on both sides will cost about £160.
Plywood is often cheaper when purchased through a CNC who buy in bulk and pass on their savings to customers. Workshops will charge about £80 per sheet for Grade BB/BB plywood. Cutting costs are usually about £70 per standard 2440mm x 1220mm sheet, and costs will vary depending on the size of your order.
All prices above are approximate and exclude VAT and delivery charges. Like other building materials, plywood is prone to price fluctuations and costs can vary from one month to the next.
Plywood Loft Interior - Harrow Road - O'Sullivan Skoufoglou - Photography by Stale Eriksen
Plywood wall panelling
Premium Grade B/BB birch plywood or carefully selected Grade BB/BB birch is suitable for panelling to rooms which demand a high-quality finish, such as living spaces.
Lower-grade plywood is perfectly suited to utilitarian spaces such as sheds and garages, and provides a secure surface for fixing shelving and hooks. Grade WG birch ply or 11/111 grade spruce is ideal.
Preparation and substates
Before installing plywood panelling, it’s important to lie the sheets flat in the room for at least 24 hours (or 48 hours in humid spaces) to allow the material to acclimatise to internal conditions and prevent warping.
The best way to achieve a flat finished surface is to install panels on timber battens.This not only ensures the panel is securely in place but also creates a useful space behind for services and thermal insulation.
Set out the supporting battens to suit the size and orientation of your finished panels, ensuring that the spaces between the battens are between 400mm-600mm apart to prevent warping.
Plywood panelling can be fixed directly to the framework of a stud partition, subject to site quality.
Avoid gluing directly to a flat substrate – this is because plywood expands and contracts at a different rate to other materials and could work loose overtime.
Fixing methods
Face fixing is the simplest method of securing plywood panelling. Screws should be at least 2.5 times the thickness of the sheet and set out at 150mm centres along edges and 300mm centres elsewhere. Edge fixings should be inset at a distance of at least the thickness of the sheet.
A quality flooring screw such as Reisser Torx Diamond Point Flooring Screw or Lost Tite Screw will provide a strong, secret fixing. Once fixed in place, they are barely visible and require only a small amount of filler to conceal the screw head.
Alternatively, fixings can be clearly expressed and incorporated into the design.
For a fully concealed fixing, consider a split batten system. One part of the fixing is secured to the back of the panel and the other to the wall substrate. Panels are then lifted and hooked into place. When designing the wall layout, it’s important to factor in clearance along the top (or side if using the patented Button-fix system) to enable the panels to be manoeuvred into place.
If your panels require a lot of cut-outs for items such power sockets, consider a screw fixing rather than a split batten system. Securing panels with split battens requires you to work blind (you cannot see the fixings when securing the panels in place) which makes it difficult to set out multiple cut-outs.
If secret fixing is paramount to your design, appoint an experienced joiner and budget for the additional time it will take to prepare and install.
Whichever fixing system you use, it’s important you leave a nominal gap between each panel for expansion. 2-3mm is normally sufficient.
Plywood ceilings
Ceilings can be lined in a similar manner to walls, as outlined above.
Alternatively, joists and rafters can be exposed, and plywood installed on top or between to create a finished soffit.
When exposing structural elements, design consideration needs to be given to the parts of the building that would normally be concealed by the interior lining – electrical cabling, ducting, pipework, insulation etc. In some situations, fire retardant panels may be required to ensure the construction meets building regulations.
Exposed Ceiling - Quarter Glass House - Proctor and Shaw Architects - Photography by Stale Eriksen
Plywood flooring
Exposed plywood flooring is only advisable in low traffic areas. If installed in a high footfall space, such as a hallway, the facing veneer will wear through overtime resulting in an unsightly finish that is difficult to repair.
As well as birch plywood, consider high-grade spruce plywood for its slightly thicker veneers. 21mm thick, 7-ply, Wisa-Spruce plywood works well.
Glue down to the sub-floor with a high-quality engineered timber flooring adhesive, such as Bona R848, and secure in place with flooring screws. To conceal screw heads, form rebated or tongue and groove joints along the edges of the plywood (this will also help the boards fit snugly together) and screw down on an angle through the joint before the next board is placed on top.
Apply a high-traffic primer and varnish finish for maximum protection.
Spruce Plywood Floor and Walls - Gallery House - Studio Octopi - Photography by Julian Lanoo
Plywood kitchens and storage units
Kitchen and storage cupboard door fronts are best formed in 21mm thick birch plywood to allow hinges and handles to be securely routed into the surface. Use 18mm plywood for carcasses.
If you’re installing exposed plywood fronts, use the highest grade you can afford. Grade BB/BB birch plywood can work well if the plug marks are carefully managed. Match the grain between doors fronts wherever possible and always orientate the grain in a consistent direction. Alternating the grain will detract from the overall aesthetic.
Apply a real wood veneer to birch plywood if you want a different timber finish.
For coloured doors, an off-site spray finish will deliver the best painted finish. Alternatively, apply a high-pressure laminate for the ultimate wipe-down surface. Leave recessed handles and edges exposed to reveal accents of the natural veneer behind for visual interest.
There are several online companies who sell pre-manufactured plywood door fronts that work with standard kitchen units, if you do not want to make your own – Plykea, Custom Fronts, Naked Doors etc – but expect higher costs and longer lead-in times.
To save costs and speed up delivery, consider making your own door fronts and pairing them with standard kitchen and storage units. Doors can be made by a joiner or CNC workshop relatively quickly.
Plywood Kitchen - No 49 - 31/44 Architects - Photography by Anna Stathaki
Plywood stairs
Birch plywood is an excellent material for staircases. It is structurally strong and feels encouragingly solid under foot.
Combine two layers of 18mm plywood to form rigid stringers: treads are best constructed in 24mm thick plywood while 12mm is suitable for risers. The profile of the stair flight can be routed into the stringer so treads and risers can be accurately slotted into position.
For a minimalist aesthetic, create flat panel balustrades by cutting sheets top and bottom to suit the pitch of the stair and secure to the outside of the stringer. Open balustrades can be created by cutting openings into sheets or rebating sections of plywood into a top and bottom rail. Use rebated joints, strong wood adhesive and flooring screws to secure parts in place.
Finish plywood stairs with paint or a high-traffic varnish – see below section.
Plywood Staircase - Step House - Grey Griffiths - Photography by Adam Scott
How to finish plywood
Unlike other sheet materials, plywood is relatively easy to finish on site.
Before decoration, fill any surface imperfections with a non-acrylic water-based filler, such as Osmo Woodfiller (or make your own by mixing sawdust with PVA glue) then lightly sand with 240 or 280 grit sandpaper.
Once the surface has been prepared, apply a finish of your choosing. One of the best ways to finish plywood is with a hard wax oil. Environmentally sustainable and low in VOCs, they bring out the natural grain of the wood, form a durable protective layer and protect against UV light which yellows timber over time. For best results, apply two coats with a non-abrasive pad, leaving each coat to dry for 8-10 hours, or as recommended by the manufacturer. Lightly sand between coats.
All clear oils and varnishes, regardless of the manufacturer, will slightly darken the plywood as soon as they are applied to the surface. If you’re using a light coloured plywood and want to maintain the pale colouration of the unfinished board, consider a white tinted hard wax oil to balance out the effect of the oil.
Hard wax oils provide an excellent finish but may require a little maintenance in areas under heavy use. For a more robust finish, consider Bona’s range of waterborne primers and varnish topcoats. They are expensive but offer unrivalled quality and performance. Primers come in a range of clear and white tinted options, and varnishes are available in different sheens and levels of durability. While the products are designed for flooring applications, Bona Novia and Bona Mega work well on general joinery items and Bona Traffic HD on flooring and stairs.
Consider an off-site lacquered finish if you are aiming to achieve the highest possible finish. Workshops will charge in the region of £100-150 /sqm plus the cost of the plywood itself.
White Tinted Birch Plywood Cupboards - Biscuit Factory Apartments - Superblk - Photography by Nicholas Worley
Which plywood is best for wall panelling?
For living spaces, premium Grade B/BB birch plywood will ensure a high-quality finished surface, while commercial Grade BB/BB birch can offer excellent results at lower cost if plug marks are carefully managed.
Grade11/111 spruce is ideal for utilitarian spaces such as sheds and garages, providing a secure surface for fixing shelving and hooks.
What thickness plywood should l use for wall panelling?
12mm thick plywood is suitable for most interior linings. Any thinner and the panels are prone to warp, while thicker panels are difficult to handle and fix.
Is plywood more expensive than plasterboard?
Plywood panelling can actually work out cheaper than plasterboard. Plasterboard needs to be skimmed by a skilled plasterer, sealed and then decorated with at least two coats of paint. Plywood panels, on the other hand, require fewer processes to finish and as a result can be installed much quicker – potentially saving you time and money.
The cost of plywood panelling is dependent on three main factors: 1- the type of plywood, 2- how it is fixed, and 3- how it is finished. A wall lined in commercial Grade BB/BB birch plywood, face-fixed and finished with hard wax oil, can work out cheaper than painted plasterwork. However, a wall lined in Grade S/BB plywood, secretly fixed and spray finished off site is likely to be more expensive.
Is plywood waterproof?
Only genuine marine plywood used in the boating industry, made from only select tropical hardwood to BS1088 standard, is highly water resistant. Other types of plywood are not waterproof.
The phenolic resin adhesive used to bond the individual veneer layers together is waterproof. The veneer layers themselves, however, are not. Therefore, when plywood is exposed to wet conditions, the veneers absorb water, leading the plywood to delaminate and rot.
How do I finish plywood?
A hard wax oil or quality water-based polyurethane varnish will provide an environmentally friendly water-resistant finish suitable for most interior uses.
Can I use plywood as a finish in a bathroom?
Yes, but not in wet areas such as shower enclosures – see above. A dimensionally stable plywood such as birch, finished with a hard wax oil or water based polyurethane varnish, can withstand humidity and be used in other parts of a bathroom. Ensure your bathroom has good levels of ventilation.
Can I use plywood for flooring?
Yes, but it should only be used in low-traffic areas. Plywood is made from thin veneers of wood and the facing veneer can wear through over time if installed in high footfall areas. You should finish plywood flooring with a high-traffic varnish to improve durability.
Is plywood sustainable?
Nordic birch and spruce plywood are highly sustainable. Plywood manufactured from slow-grown tropical hardwood is not sustainable. Always source plywood that carries FSC or PEFC certification.
Is plywood fire resistant?
Untreated plywood has a similar fire resistance to other wood-based panel products such as MDF and OSB and will typically achieve a Euroclass D or E fire rating (nominal resistance). Manufactured fire-retardant plywood boards can achieve Euroclass B and are highly fire resistant.
Is plywood strong?
Yes. Its alternating glued veneers give it excellent strength and rigidity.
Is plywood toxic?
Plywood manufactured using phenol-formaldehyde resin adhesives is non-toxic. This includes Nordic birch and spruce plywood.
Looking for more inspiration? Take a look at five plywood home interiors that show off the material’s potential.
The information in this article is for general guidance only. Before undertaking any building project, seek professional advice from an architect.
References:
In addition to the project and product references noted above, information from the following sources were referred to during the writing of this article.
Online:
Books:
Architect’s Pocket Book by Charlotte Baden-Powell, Architectural Press
Eames by Gloria Koenig, Taschen
About the author: Aron Coates is an architect with over two decades of experience, encompassing projects ranging from the restoration of historic buildings to the design of contemporary homes.
The information provided in this article is intended for general guidance and educational purposes only. At Designs in Detail, we advise you appoint a skilled residential architect to provide specific expert advice for your project.
