Questions about ESSDECK Max

Questions and answers about our ESSDECK Max decking screw – developed in collaboration with professional craftsmen.

What does the updated steel grade of ESSDECK Max mean?

We’ve switched to 10B21 steel in our ESSDECK Max with CorrSeal surface treatment. 10B21 contains Boron, which improves the hardenability of the screw.

In practice, this results in a stronger and more flexible steel. Screw manufacturers have specifications for each screw’s surface hardness and core hardness. We’ve adjusted the specification for the surface hardness of ESSDECK Max in order to make it slightly softer, meaning the screw tolerates more movement, BUT retains all its strength.

In short, the updated steel grade provides a screw that’s easier to work with yet responsive to the decking’s movements. We recommend installation according to Swedish Wood’s recommendations; please read more in our Decking Guide.

How does the ESSDECK thread pitch affect the screw’s clamping force?

We utilise the thread design on the different parts of the screw to help the head clamp the board in place. The threads at the tip of ESSDECK Max are sparser than the threads higher up the screw.

This means that when the lower threads (which bite into the timber faster) reach the joist and the upper threads (which bite into the timber more slowly) catch hold of the decking board, the joist and the decking board are pressed together with a strong clamping force.

This makes it possible for ESSDECK Max to easily secure propeller boards in place! In addition, the upper thread provides holding power when installed, which makes a smaller head with the same or better holding power possible.

Will using warped boards affect the structure of the build?

No, it won’t. Once the board is installed, it’s held firmly in place. The advantage of the clamping thread on ESSDECK Max is it ensures the same aesthetically pleasing installation with a warped board (propeller board), since the screw takes the board down with it instead of the screw being deeply countersunk, which is often the case when you attempt to install a warped board using traditional decking screws.

How close to the crosscut end can you use ESSDECK Max?

We’re very sorry but it’s not possible to give an exact answer to this question, as this will depend on many factors, including the timber.

Generally speaking, however, you can install ESSDECK Max closer to a crosscut end than many other screws, thanks to the threads at the tip milling as opposed to cutting the hole.

The disadvantage of screws with cutting grooves is that during installation the cut quickly fills with wood chips so this feature soon becomes ineffectual and pushes the timber apart instead – this doesn’t happen with ESSDECK Max.

Always follow the recommendations from your timber supplier.

Which screw surface treatment should I choose?

It is important to choose decking screws according to where you’re building your timber deck. ESSDECK Max is available in A2, A4 and CorrSeal (C4) surface treatment, below is some brief information on when we recommend you to use each surface treatment.

It is important to always check the recommendations from your timber supplier.


Stainless A4 screw is made of unhardened acid-proof steel with the highest corrosivity class C5. While this screw can be used for all timber decking structures, it should definitely be used in aggressive environments, e.g. by pools and jetties, and for timber decks in coastal locations near salt water.

Stainless A4 screws are also recommended if you’re building a deck with tropical hardwoods. Stainless A4 is a flexible material, ideal when the screw needs to absorb large structural movements.


Stainless A2 is made of unhardened steel with corrosivity class C4.
We recommend this screw for structures near lakes or brackish water.
We also recommend it for railings, fences and steps for your wood deck, since it provides good resistance to corrosion and movements.


ESSVE’s CorrSeal surface treatment with corrosivity class C4 is an alternative to the anti-corrosion surface treatments of A2 and A4.

This surface treatment offers good corrosion protection (rust prevention) – well suited for the Nordic climate. You can use CorrSeal-treated screws for stable and low decking structures in environments not considered to be aggressive.

To sum up: a stainless screw is not hardened, which makes it tougher. This means it can absorb movements in the wood or structure better than standard hardened screws.

Would you like to know more about steel grades and surface treatments?

Read more here.