Deck Framing Costs; With Deck Size Examples

Decking framing, the substructure that supports your deck, is essential to a good deck. Several factors affect the cost of deck framing. These factors will change individual deck framing costs.  

On average, the cost to frame a deck is between $6-10 a square foot, including material. Joist size and span play an important factor in both material and labour cost to frame a deck. A larger deck with standard joist dimensions with less waste will cost less to frame. Decking material and direction also affects deck framing costs.

The following are two charts of standard deck dimensions along with average framing costs, material plus labour. I have divided them into two groups for comparison based on joist sizes. The first group are decks with 2×8 joist with spans less than 12’. The next one is decks with 2×10 joist for spans greater than 12’. Some of these decks can be built to code while using smaller dimensions of joists, but these are common joists selections.

Decks with 2×8 joist, Spans less than 12’0”

Decks with 2×10 joists, Spans greater than 12’0”

Not included in these numbers are deck piles as they vary according to regions. Also, decking and railing are not included; this is just the substructure of the deck. Starting from the ground support, ending before the decking is installed. As with all averages, some exceptions and items that will increase or decrease costs. Here are a few factors to consider when determining deck framing costs.

Decreasing on Centre Joist Spacing will increase Deck Framing Costs

The closer the joists are, the higher your framing material costs will be. Because of joist span limitations and decking, I like to frame decks with joist at 16” on centre. There is two reasons why you may want to reduce spacing to 12” on centre.

Thinner or composite decking with scallops grooved into the underside will often require smaller joist spacing — the decking requiring additional support. When running composite decking at an angle across the joist will also require smaller joist spacing, like 12” on centre.

Another reason for increasing joist is that 12” on centre allow for longer joist’s spans. For example, if you wanted to have the deck beam at 13’ from the ledger but didn’t want to use 2×10, spacing 2×8 joist at 12’” on centre will allow the joist to span that gap.

Adjusting joist for spanning is unusual, more commonly is decking requirement. But if changing joist from 16” on centre to 12” will increase the material cost about 20%. You will also have about 20% more joist to install increasing labour about the same amount.

The Span of the Joist Effects Deck Framing Costs

The spanning of joist determines the required depth of the joist. Most decks are framed with 2×8 joists as they have sufficient span strength, and guard rails can be attached to them. But if you require a span greater then 12’, the joist will need to be upgraded to 2x10s.

The extra depth, 2x10s will also provide a firmer feeling deck — the joist springing less with every step. A firmness appreciated by some.

Upgrading joists from 2×8 to 2×10 joists will increase framing material costs by about 25%. Where the extra span is needed to reduce beams, this is an easy choice. The additional span will pay dividends in reduce posts and beams required. All while allowing you to enjoy a larger deck.

Height of Deck raising framing costs

Most backyard decks are a nice comfortable working height of less than 3’ from the ground. Allowing work to be done while standing on the ground, saving both time and energy. Decks higher than 3’ from the ground, framing must be done from ladders or scaffolding. Both require additional time in setting up and climbing up and down.

For example, a basement walkout, with a 9’ high deck off the main floor, will require an additional length of post, increasing framing material cost. A more significant impact will be the additional cost in labour working from ladders. Climbing up and down ladder slows down construction and often requires an additional labour to assist with framing. Passing up material and grabbing tools on the ground.

Increasing a decks height from 3’ to 9’ will increase labour cost roughly 25% plus the length of the additional post. The view is better, but you will have to pay for it.

Decking material impacting framing Costs

As I already mentioned, some composite decking will require closer spacing of joist, but composite decking will also require additional blocking. With composite decking, everything needs to be supported as it’s not considered a structural material; therefore. Harder to quantify with each individual decking layout determining the amount of blocking required but often will increase framing cost by 10%.  It is not out of the usual to spend an additional day installing blocking for composite decking.

It has almost become standard for me to picture frame decks that I build. But picture framing of the decking not only requires additional decking but also framing to support it. The picture framing hides the unsightly end cuts of composite decking. It also improves the durability and look of wood decking. The additional joist and blocks to support the perimeter decking can add $60-120 in additional material costs plus labour for a standard rectangle deck. 

Changing the joist direction from perpendicular to 45° will improve the look of the deck significantly but increasing costs by about 20%.

As I mentioned before, angle decking or herringbone will often require additional joists to support the decking. When decking runs at a 45° in increase the actual span of the decking by 1.414, changing 16” into 22 5/8”. Composite decking cannot span that great of distance. Requiring joists to be framed at 12” on centre reduces the angle decking span to 17”. Just close enough to support composite decking during the hot summer days.

The terrain of the Yard can change Deck framing costs

This one is hard to quantify, but how level your yard is will affect how much time it takes to frame. A level yard to work makes framing easy. If the deck is over a steep incline requiring ingenuity to place material and raises beams, labour costs will increase.

Also, large boulders or trees will need to be framed around, requiring additional time and possibly material.  Windows wells along the house, breaking up the ledger will require additional joists to support flush beams to bridge the gap around the window well. The goal is the deck, but the yard will change how much it costs.

The spacing of deck footings changing Beam costs

The closer the footing, the smaller the required beam. A double edge sword as often adding an additional beam ply or increasing the depth of the beams will save you hours in digging concrete piles to support the deck. Let alone the saving in less concrete. One 4’ concrete pile will cost you $40 in concrete. An additional ply will save you both in time and material costs but still will increase framing costs.

Structural Deck Hardware Increasing Framing Costs

There are many ways to fasten together deck framing. Lots of hardware will save you time and increase the strength of the deck, along with improving the appearance. Especially being true with raised decks. Black ornamental ties will not only provide a strong connection but also add flair to the underside of your deck. But this flair is not cheap; an ornamental tie can cost anywhere from a couple of bucks to hundreds. They will improve the look of your deck while you are sitting under it, enjoying the shade on your patio, but it will come at a price.

If the underside of the deck is exposed, it is worth it to upgrade to ornamental ties as the look will increase the value of your deck. A couple of hundred dollars extra will pay for itself in a nicer looking deck, especially if you are using the space underneath. But this will increase the cost to frame your raised deck.

Going alone or hiring a pro?

Hiring a professional to frame your deck will increase the cost two to three times the cost of material. How much more depends on the carpenter’s experience and the complexity of the deck. Building a 12’x12’ ground level deck will cost around $400 in framing material. Hiring a deck builder can increase that close to $1200.

An experienced deck builder brings years of deck building skills and knowledge to your deck which can improve both the function and look of your deck. The value of experience in framing your deck will increase in proportion to increased framing costs.  

Experience is Gold!

Through my many years working in construction, I can confidently say that it’s the structure that you “never see” that changes the game in the appearance. Both when you are doing the finishing work and years later, the unseen holds it all together.

If you have the skills and the know-how, doing it yourself will save you over half the cost of your deck framing. Take some time to do your research, learn what you don’t know before you build not after costly material needs to be replaced. Deck framing is fun, and I have enjoyed it for years. Have fun, pay attention to the important things without having the little things bog you down. Knowledge, experience and research will let you know which is which.

If you go with a pro, it will cost you a little more but can be worth it. Regardless of what you pay for the material, if its not put together correctly, its junk. An experienced deck builder will assure that your deck is built properly, allowing you to enjoy your it for years to come.