Top mounted
decking screws
Top mounted fastening is the most common method of decking assembly and can be made with both surface-treated or stainless decking screws depending on the location of the decking. In coastal or exposed areas, as well as fastening in harder types of wood, a stainless screw is always recommended.
DECK+ A4
4,2x35 - 4,8x75
Classic NKT decking screw in acid-resistant stainless steel for coastal mounting and extra-long durability. Countersunk head provides a nice finish. Proofpoint® tip reduces risk of cracking.
DECK+ A2
4,2x42 - 4,8x75
Classic NKT decking screw in stainless steel that ensures long durability. Countersunk head provides a nice finish. Proofpoint® tip reduces risk of cracking.
DECK+ OUTDOOR
4,5x42 - 4,8x75
Classic NKT decking screw with surface treatment for weather-resistant use in inland climates. Countersunk head provides a nice finish. Proofpoint® tip reduces risk of cracking.
DECK+ High End A4
6,0x60
Powerful NKT decking screw in acid-resistant stainless steel, specially developed for hardwood. Cylinder head and double threads with locking function.
SPUN®+ SUH A4
3,5x15 - 6,0x140
Powerful all-round NKT screw in acid-proof stainless steel. Conical countersunk head with an optimized tip. The safe choice for all types of decking. Suitable for plugging.
Hidden decking
system
Achieving the correct placement for hidden decking fastening can be tricky, therefore we have developed Deck Pro®. The NKT Fasteners tool is specially developed with focus on ergonomics and efficiency and fits all common board widths. Deck Pro screws for hidden mounting are developed together with the Deck Pro tool and ensures maximum mounting force for a sustainable result.
DECK PRO® A4
4,5 x 60
Powerful NKT decking screw in acid-resistant stainless steel, specially developed for hardwood. Cylinder head and double threads with locking function.
DECK PRO® OUTDOOR
4,5 x 60
Powerful all-round NKT screw in acid-proof stainless steel. Conical countersunk head with an optimized tip. The safe choice for all types of decking.
DECK PRO®
Tool
Achieving the correct placement for hidden decking fastening can be tricky, therefore we have developed Deck Pro®.
NKT Fasteners is a Nordic brand with over 120 years of experience with fastening solutions specially developed and tested for harsh climates. We work closely with the end user to constantly developing and optimizing our products and solutions, then the work with fastening becomes safe, simple and effective as possible, without compromising on the quality.
GUIDE: Choose the
right NKT decking screw
In order to build a deck with a nice finish that lasts for many years to come there are a couple of things that are important to consider.
Choosing a high qulity decking screw based on the environment, type of wood and according to the industry recommendations are important factors in order to achieve a great result. Follow our step by step guide below to find the perfect screw to your deck!
Choose decking screw: Step By Step
Step 1
Choose the right decking screw for the environment
The first step is to consider the environment of where your deck will be built. Rule of thumb is the more agressive environment - the better protection against corrosion is required. However, the flexibility of the screw should also be taken into consideration as larger decks tend to have bigger movements that puts dynamic pressure on the screw.
​
If your deck will be exposed to any type of chemicals, is located in a coastal area or nearby a swimming pool, our stainless decking screws Deck+ A4 or Deck+ A2 is the right choice. The same applies to a XL-sized deck, or if built high above ground as the stainless screws tend to be more flexible and thereby better withstands the dynamic movements. If built in a inland climate our top-selling Deck+ outdoor screw with a weather resistant surface treatment is the ideal choice.
Step 2
Consider your choice of decking timber
The most common type of decking timber are so called soft wood, with a volume weight up to 450 kg/m3. For this type of wood any of our Deck+ screws can be used without predrilling.
For the slightly more dense type of timber, between 450-500 kr/m3, such as Douglas fir or cedarwood, any of our Deck+ A2 or Deck+ A4 decking screws are recommended.
​
If building a deck using hardwood with a density over 500 kr/m3 we recommend predrilling along with our allround screw SPUN+ SUH A4, or our Deck+ HE A4 which is specifically developed for mounting in hardwood.
Step 3
Choose the right screw dimensions
Our NKT Fasteners decking scews are developed according to industry recommendations. This means that the neck of the Deck+ screw equals the thickness of the board, in order to achieve a clamping effect. Further, the full length of the screw should be at least double the thickness of the decking board for optimal durability and strength .
Step 4
Choose way of mounting
The traditional way of mounting a deck is by top-mounted screws, which is suitable for all types of timber. For top mounting we recommend our classic DECK+ screws, or for hardwood choose DECK+ HE or SPUN+ SUH.
​
For a more exclusive look the deck could be plugged, meaning the screws are hidden under a wooden plug using the same type of wood as the decking boards. When plugging we recommend our SPUN+ SUH screw in stainless steel for an optimal clamping effect.
​
Lately, the interest have grown for another type of hidden mounting where the screws are mounted from the side of the board using a hidden mounting tool. Only recommended for softer types of timber. For this type of mounting, use Deck Pro tool and Deck Pro screws.
Find the perfect length for your deck in the table below.
-
What board width does the Deck Pro tool work for?Deck Pro fits all standard board widths on the market, the same tool fits boards from 85-150 mm in width. For boards over 150 mm in width, 3 attachment points are generally recommended, where we instead recommend a top-mounted solution.
-
What board thicknesses can be used when mounting Deck Pro screws?Deck Pro screws have the dimension 4.5x60 and fit all boards from 18-34 mm in thickness. However, it may not be installed in hardwood or other types of exotic wood-types.
-
Can I use Deck Pro on hardwood?No, Deck Pro is recommended for most types of wood, but not for hard wood. When building decks with hard wood, you should instead use one of our top-mounted decking screws with a thickness of at least 5 mm, such as Deck+ HE or SPUN+ SUH.
-
How does hidden montage work? Can you see the screw holes?When mounting your screws with the Deck Pro tool, the placement of the screw is optimized to be as far down on the edge as possible, without compromising with the strength and durability of the installation. If you look closely at an individually mounted screw you will be able to get a glimpse of the screw hole. However, if you look at the decking from a normal distance the impression is that the screws are "invisible".
-
Is there a risk of water seeping into the wood where the screws are mounted?The Deck Pro screw is developed with a cylindrical head that closes the hole during installation, this will prevent water from penetrating into the wood.
-
How do I mount in angles where the tool cannot be used?The screw has a reduced drill tip that provides a quick start in tricky angles, this means that the screw can be installed without the tool if needed.
-
How big is the distance between the boards?When buying the Deck Pro tool, distance blocks are included that allows the distance between the boards to be adjusted, from 3 mm up to 7.5 mm. The tool comes pre-mounted with a 6 mm distance in accordance with building standards but can easily be changed if a different distance is desired.
-
Which screws fits the Deck Pro tool?The Deck Pro is a system solution where screws and bits that are specially developed with the tool. Generally, other hidden screws on the market have too large heads and will therefore not fit our tool. However, our Deck Pro screw works well with other tools on the market as well.
-
How is the Deck Pro different from other tools on the market?The Deck Pro tool has a unique adjustment function which means that one and the same tool can be easily adapted to all common deck widths on the market, from 85-150 mm. Other tools on the market today require two different tools, one for thinner and one for wider boards. The Deck pro handle is developed with a focus on optimization and ergonomics and can withstand up to 100 kg of direct load. Many also feel that the Deck Pro is more stable and stands more stable against the board.
-
Why is the minimum distance 3 mm?General building standards recommend 6 mm distance between each decking board, taking into account that the wood can expand or contract up to 5 mm depending on current prevailing humidity. To avoid larger gaps in the wood when mounting in damp conditions, Deck Pro is possible to adapt into a minimum distance of 3 mm. However, it is important to remember that smaller distances between the boards lead to an increased risk of boards colliding. We always recommend to follow national building standards.
-
How do you mount the boards against the wall?For a hidden assembly of a board that lies against the wall there is a smart little trick. Pre-assemble the board onto a shorter support beam using the Deck Pro tool. Further, insert the pre-assembled board against the wall and then attach the support beam to the primary beam.
