How to lay out, place, & secure decking: the deck flooring.

We describe how to lay out and fasten deck boards to the deck floor joist structure and how to decide on the appropriate deck board gap.

Choices of deck board fastener types and methods include nails, screws, clips, and a wide variety of hidden deck board fastener systems that we describe here as well.

Page top photo: the author was lead designer, carpenter for this outdoor deck used as a performance stage in Two Harbors, Minnesota. We used 5/4" thick tongue and groove boards as the decking material.

This article series describes construction details for decks and porches, including deck structures, floors, and other components like deck stairs and railings.

Deck Board Installation: how to connect decking to the deck framing

The quickest and the least expensive way to fasten decking boards is to nail them on. Be sure to use ring-shank or spiral-groove nails, which hold much better than common nails.

[Click to enlarge any image]

For the tightest connection, it is hard to beat decking screws.

The one shortcoming that both fasteners share is that they are visible on the deck surface. If you would rather not have to see screw or nail heads on your deck,

Be sure to match the fastener you use with the decking you are installing. Galvanized fasteners work fine on pressure-treated lumber, while stainless steel is a better choice with redwood,

Western red cedar, and tropical hardwoods. Composite decking can usually be installed with galvanized fasteners, but it is smart to check with the manufacturer.

Stainless steel deck board screws should also be used near salt water.

In terms of fastener lengths, use 3-inch screws or 12d nails for 2 X 4 or 2 x 6 decking, and 2 1/2inch screws or 10d nails for 5/4 X 4 or % x 6 decking.

The job will go quicker if you scatter boards for 10 to 15 rows of decking across the joists first.

That way you will not have far to reach for a new board as you work.

This is particularly important if you have to deal with butt joints; arrange the decking so that the joints are staggered before you start driving fasteners.

How Much to Space The Deck Boards: will someone fall into the gap?

Gaps between decking boards are necessary to allow water to drain, but should not be so large that small objects fall through or toes get caught.

A 1/8-inch gap is a reasonable end-target, but since wood decking often shrinks after it has been installed, this shrinkage must be taken into account during installation.

The photo (above left) shows an older wood deck that has good drainage; The gaps between these boards averaged about 3/16".

In the composite deck board installation shown below, you'll see that the installers maintained a deck board gap to provide drainage lest the surface pond water leading to ice or algae slip trip and fall hazards even where rot is not a worry.

Determining how much your decking is likely to shrink can be a little difficult. Boards that are wet and heavy will likely shrink the most.

These boards can usually be installed tight against each other; over the course of a year or so they will shrink enough to create a satisfactory gap.

Dry, kiln-dried boards will not shrink much at all, however, and composite or synthetic deck boards (photo at left) should not shrink at all and so should be installed with a 1/8-inch gap.

An 8d common nail makes a useful spacer, although inexpensive deck board-spacing tools are also available (I've never used one - DF)

Composite or synthetic deck boards such as shown in our photo are detailed separately

at COMPOSITE DECK BOARDS.

Also see DECK BOARD GAPS & SPACING - best construction practices

Choices of Deck Board Fastening Methods: nails, screws, hidden fasteners, clips, biscuits, adhesives

Decking has been traditionally installed with fasteners that are driven through the tops of the board.

In some people's opinion the visible fastener heads detract at least a little from the appearance of a deck surface.

At worst, poorly driven fasteners can pop loose, cause splits and stains in decking boards, and allow water to penetrate and damage the wood.

Fastener heads may also protrude over time as the decking shrinks, requiring that they be reseated.

Our photo above shows one of the crew using a nail-set to set the power-driven galvanized fasteners used in the last boards installed at the SummerBlue Arts Camp stage construction project.

Most of these boards were blind-nailed through the tongue into the joists below, leaving no visible fasteners at all. But the last few boards required surface nailing that had to be set.

The original construction, installation and long term performance of this outdoor performing arts stage floor are described in a series of articles beginning

at BATTER BOARDS LAYOUT METHOD.

Types of Hidden Deck Board Fastening Systems

If you would rather not accept such compromises, consider a hidden fastener system.

The fasteners are attached to either the edges or the bottoms of the decking boards. Although these systems differ in expense and installation, you can be assured that any of them will cost more and require more time and effort than the traditional method.

In addition to deck board clip systems (described below) other hidden fastener systems include nailing through the tongue of T&G 2x6 or 5/4" deck boards (photo above), and proprietary deck fastening screws designed to secure deck boards by blind screwing through the deck board edge using both special screws and in some cases a proprietary application tool as well.

National Nail Corporation's Camo Hidden Deck Fastening System is designed for use with Camo's Camo Marksman Tools only. Shown at left is the Camo Marksman Pro tool used to install the company's hidden and proprietary edge-driven deck screws.

The CAMO tool in the carpenter's hand assures that the proprietary deck screw is driven at the correct position in the edge of the deck board and on the proper angle.

Notice that the leading edge of the tool (lower left in our photo) slips into and assures a deck board gap too.[8]

If you decide to use a hidden fastener system, check with the manufacturer for more detailed instructions.

Make sure that the system you choose is compatible with the type of decking you use. Excessive shrinkage of the decking can weaken the bonds of many hidden fastener systems, so it is wise to use decking that is as dry as possible.

Using Deck Clips to Mount Decking Boards

Deck clips are attached to the edges of decking boards. Most manufacturers instruct you to toenail the first row of decking to the joists before you begin using clips on subsequent rows. One advantage of clips is that, because of their location, they provide a uniform gap between boards.

Watch out:  deck clips are not a one-size-fits-all product. Shown at left is the Tiger Claw TC-35 deck clip specifically sized to provide a hidden mounting system for composite or synthetic deck boards such as those shown in our photograph above.

When installing composite decking using clips like the TC-35 as well as in some other deck clip products, some special procedures are required for successful deck board installation. [6]

The clip has no connection with the joists at all.

For composite decking, place the first deck board against the building and screw it down to the deck floor joists along the building edge of the board.

Subsequent boards are placed against the starter board and clip on a modest angle to make setting the next board in place into the clip. We don't try to drive the entire board into place parallel to the preceding board at one time.

Deck floor framing tip: when hammering deck boards into deck clips, use a 4-ft 2x4 as a hammer-board placed against the board being installed.

Always hammer against the exposed edge of the hammer board to avoid damaging the edges of the deck boards themselves.

You may need to use a flooring hammer or even a sledgehammer to force boards into the hidden clips. .[6]

For wood decking using deck clips the first board is nailed or screwed to the joists as above. To install the clip, you drive a nail at an angle through the hole in the vertical neck of the clip, and on through the decking and into the joist.

Another nail ties the clip directly to the joist. The next board must be forced into the sharp prong on the clip, and then attached with another clip on the other side.

The bases of the deck board clips hold the decking board off the joist surface, a detail that encourages drying. Since you cannot install side-by-side clips at a single joist location, these clips are best used for a deck in which butt joints fall over double joists.

The IPE Clip IC100EX-SBR Extreme Short Brown Hidden Deck Fasteners are a colored non-metallic deck clip. We found this product review on Amazon:

The process of installing them takes a lot longer than using screws through the face of the boards. That said the look of not having any visible screws it awesome! If you have more money than time, buy the wood pre slotted, otherwise buy a biscuit joiner and do it yourself.

I was using a very hard Brazilian wood, so I had to pre drill each hole, but after after a while you get a system down and it goes much quicker.

Lay board down, Slot above every joist(if not pre slotted) Place clip in slot Pre drill clip/slot above every joist (can maybe skip this step if using softer wood, pine, composite etc...)

Insert Screws and tighten Don't over tighten as the screw will pull through the clip.

If this happens back out screw and flip the clip and tighten against the other side. - product search, Amazon.com 4/28/2013

Simpson Strong Tie provides hidden deck board fasteners, # 175-EB TYS.

Other deck clips including clips made of plastic, stainless steel or aluminum, combine a horizontal clip that inserts into a groove cut into the edge of the deck board with a screw that fastens the clip to the joist surface. The next deck board marries its groove or rabbet cut into the opposing side of the same clip.

Watch out: I know how exciting it is to just start building and to use the product instructions just to hold your sandwich, but really, be sure to read the instructions for the specific deck clip system you are planning to use. You may find that the use of construction adhesive is also required for a successful installation.

How to Use Metal Bracket Fasteners for Installing Decking

Installation of a metal bracket system is labor intensive (be prepared to drive lots of screws), but the connection it produces is strong and secure.

Brackets are available in both galvanized and stainless steel, with screws to accommodate either 2x or 5/4 decking. The brackets are first installed at the sides of the joists, and then attached to the decking with screws driven upward. If you can’t work from beneath the deck, this second step will be somewhat awkward, although still doable.

1. Attach Deck Board Brackets to the Joists

Fasten brackets along the full length of each joist on alternating sides of the joist. Use tin snips to cut pieces to length, if necessary.

2. Connect to the Decking to the Brackets

Decking must be fastened to the brackets with screws driven from below. This is much easier to accomplish if you can work from below the deck.

How to Use Biscuit Fasteners to Install Deck Boards

Still another innovative hidden fastener system features poly-propylene biscuits and stainless- steel screws. Installation requires cutting slots into both sides of the decking boards at each joist location, a task for which you will need a biscuit joiner or a router equipped with a slot- cutting bit.

Slide the biscuits into the slots, and fasten them to the joists with screws.

Unlike most other hidden fasteners, the biscuit system places the decking directly on top of the joists. To strengthen the connection and minimize the chance of squeaks, place a bead of construction adhesive across the tops of joists before installing the decking.

The biscuits are thin enough to use with 1X decking, which makes this system particularly useful when installing tropical hardwood decking. With hard lumber, be sure to drill pilot holes before driving screws.

1. Cut the Deck Board Biscuit Slots

Set the decking board across the joists. With a biscuit joiner or a router equipped with a slot-cutting bit, cut slots centered over each joist on both sides of the board.

2.  Install the Deck Board with Adhesive

Apply a thin bead of adhesive to the tops of the joists, then slide the decking board into place against the previously installed board with the slots on that side fitting over the previously installed biscuits. Install biscuits in the slots on the exposed side of the board and drive screws through the biscuits and into the joists.

Using Construction Adhesives for Deck Board Mounting

Adhesive is used with decking in different situations.

With the biscuit fastening system, it may be used to prevent squeaks from occurring when foot traffic causes the decking to rub against the joists.

If you take this extra step, be sure to use an exterior-grade flooring adhesive, which is applied with a caulking gun.

Some professionals have also had success using only an adhesive to fasten high-priced and dimensionally stable tropical hardwood decking to the joists.

For that approach, use a fast-curing, exterior-grade polyurethane adhesive, but check with the decking manufacturer first.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Should there be a gap between two ptw deck boards side by side in parallel?

@Robert Jordan,
My question should have read: Should there be a gap between two ptw deck boards side by side in parallel?

Should there be a gap between two parallel ptw deck boards? - On 2018-12-28 1 by Robert Jordan -

Reply by (mod) - yes

In my opinion yes for better drainage. Some Builders figure that the lumber is so wet that is going to shrink so much when it dries that they leave very little gap between their deck boards.

However I prefer to leave at least the thickness of a number 10 or number 12 common nail when building a deck.

Should my deck floor connect to every deck joist?

When attaching the standard wooden deck floor using screws, is it recommended to fasten to each of the floor joists (16 inch centers)? - On 2018-08-19 by Ralph Vaughan

Reply by (mod) -

Ralph: That's a good practice when using typical 3/4" thick decking. If you're using thicker deck boards such as 5/4 or 1 1/2" thick boards, you may get away with every other joist.

Avoid roof shingle nails hitting gaps in roof decking

with architectural shingles how far should you drop the first row to keep the nails from lining up with the cracks between the decking with 1/6 decking? - On 2018-08-08 by joe frey -

Reply by (mod) -

Joe:

I'm not sure how Google led you to a deck floor page to ask about roof shingles - we are talking about roofing shingles, right?

We discuss asphalt shingle starter course nailing for two different situations: a new roof and re-roofing, as those are a bit different.

Please see these articles and let me know if questions remain:

ASPHALT SHINGLE INSTALLATION

and

ASPHALT SHINGLE RE-ROOF GUIDE

How do you suggest to cut deck boards to prevent shrinking

How do you suggest to cut deck boards to keep from shrinking - On 2017-05-24 by Lee sweatt -

Reply by (mod)

Thanks for the interesting question, Lee.

I don't think there is *any* cutting method that would prevent a wood deck board from shrinking. Shrinkage occurs, mostly across the grain of the deck boards, when the boards are wet when installed and then shrink as the boards dry out after construction.

You can take some steps to minimize un-wanted effects of board shrinkage by thinking about the gaps that you choose between boards during initial construction.

We want some gap between deck boards for drainage so that our deck doesn't pond water; If the boards are very wet at the time of construction, I leave a smaller gap between boards, perhaps just 1/8", figuring that as the boards shrink the gap will widen.

Is it normal to have to retighten screws on deck boards after shrinkage?

Is it normal to have to retighten screws on deck boards after shrinkage - On 2015-10-23 by Anonymous -

Reply by (mod) - retighten screws on deck boards after shrinkage

I'm not sure what to call "normal" anon - usually deck board screws are power-driven to below the board surface so that even after the boards dry out and shrink a bit the screws are not visible.

If your board screws were not countersunk into the boards then yes they may need to be turned down; I'm not entirely optimistic: some screws may be seized in the boards or joist below and may break when next torque is appied; if so use a large nail set to sink the screw below the board surface and then add another fresh screw close-by.

 

How to secure deck boards moving after using Trex hidden screw fasteners?

I built a sizeable Trex deck in Rolling Hills CA using a hidden screw fastening system by Trex.

The deck is supported by a stuccoed three foot high wall that covers the entire perimeter of the deck. Cracks are forming in the stucco mainly due to various small ground tremors. Would it have been wiser to face screw the deck boards to alleviate the degree of lateral movement caused by the swaying of the tremors?- On 2015-04-15 by Brian Fry -

Reply by (mod) - Trex decking fastener question

Brian

This is beyond my expertise but my OPINION is that face screwing would not have made the difference in movement that you describe. The whole structure moves against the building.

An expert examination of the crack location and pattern should be diagnostic.

My guess is that you'd need to allow for movement by separating the actual stucco from the moving attached deck structure.

...

Continue reading at DECK FLOOR INSTALLATION TIPS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• COMPOSITE DECK BOARDS
• DECK & PORCH CONSTRUCTION - home
• DECK FLOOR INSTALLATION
• DECK FLOOR INSTALLATION TIPS
• DECK FLOOR LAYOUT
• DECK FLOOR & STEP CUPPING
• GUARDRAIL CONSTRUCTION, DECKS & RAMPS

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