How to Fix a Heaving Deck

A reader wrote in with questions about why her deck is heaving up and down though seasonal changes

Dear Mike,

Two years ago, my husband and his good friend built a above ground deck for our home. All has been good, except last winter we experienced our deck start to heave upwards quite noticeably. Then in the spring, my deck returns to normal. My husband has looked under the deck for damage, nothing out of the ordinary so far. So my question for you, what causes my deck to move up and down like that?

Laura,

Manchester, NH

Dear Laura,

Thank you for writing in with your concerns regarding your deck problem. Without having a set of your existing deck plans and concrete footer depths, I can only give you a broad answer. I’ll do my best to give you some examples and solutions of what should have been done to avoid your deck heave.

Main Causes:
The most common causes of deck heaves, are caused by not having your concrete footers set deep enough below the frost line. In order to know what depth you should set your concrete footers, you should first check with your local building department. Your building department will provide you with a table chart based on your exact location. Here in Massachusetts, we have to dig our footings to a depth of 48″ inches, to be below the frost line.
How can frost make a deck heave?
How can frost make a deck that is so heavy move upward? Most all types of soils contain water and when that water freezes, the water expands to 9% it volume. The result of this volume increase, can have the ability to exert up to 50,000 lbs of pressure per square inch –now that a lot of power!


Solution:

Laura, to accurately solve your problem, tell your husband he’s gonna have to get dirty – grab a shovel and start digging! Tell your husband to follow these steps below.

1. Visit your local building department and get a copy of your building code’s footer size, depth, frost line chart;
2. Set up temporary bracing to support the area in which you plan to excavate, to evaluate your existing footer depth;
3. If your existing footer is less than the required footer depth, you need to re-pour your concrete footers, so set up temporary bracing around your entire deck;
4. Go back to your building department and apply for a building permit to repair your footings. Why? Because a building inspector is trained to properly evaluate the depth and size of your footers, to ensure the job is correctly done to code before you pour new concrete – you don’t want to do this 3 times, do you?
5. Once you have removed and dug out all of your holes to the proper depth and width, compact the soil with a tamper, so the soil isn’t loose on the bottom;
6. Go ahead and shovel in a few scoops of crushed stone around the perimeter of the footer hole;
7. Next, install your new sonotubes but don’t place it completely on the bottom, allow enough room so the concrete when poured can mushroom out – picture having a mushroom upside down;
8. Don’t pour any concrete just yet! Have your building inspector come out and evaluate your size and depths of your footers, once you pass then you can pour concrete;
9. Start reassembling your deck posts with electrogalvanized post brackets and hardware;
10. That’s it, you’re done!

Generally, Mahogany decking has been viewed by many contractors and homeowners for its decking being a hard and highly durable. Since mahogany decking is a harder more dense wood, it has the tendency not to buckle, split or warp. Also, please note Mahogany decking will be a little more expensive than pressure-treated decking, however it’s well worth the investment and looks great to home-buyers and is durable.

Fastening materials for securing Mahogany decking

As a deck contractor here in Ma., I prefer using stainless steel screws for decking installations. Other types of fasteners may not penetrate to well or not hold up to well. However, pre-drilling holes is mandatory if not using a nail gun. Even with stainless steel nails, they will bend trying to simply nail them into the mahogany wood decking. I found with using stainless steel hex head screws, you’ll ensure the maximum bond between your decking and the frame.

When installing the mahogany wood decking, I found it aesthetically most attractive to create a picture-frame on the outside perimeter of the deck surface using long Mahogany decking boards.

Once the outer frame is installed, then the main Mahogany decking boards can be simply installed within this outer framework. The result is a cleaner line when viewed from a distance or standing on the deck itself.

Regarding the mahogany railing system, screws and bolts should be used exclusively as the material use in this part of the deck is typically thicker and requires more rigidity.


Staining or Sealing Mahogany Wood Decking

Mahogany wood decking takes paint and stain well, however I have preferred to apply a clear sealer. The clear sealer enables the natural red color of the Mahogany decking to shine through, while still providing a layer of protection from the environment. Typically I re-apply the clear sealer every year to continue to preserve the color. If you do not, the Mahogany will bleach out.

If you live in Massachusetts or Rhode Island and in need of a deck contractor, feel free to click on any highlighted link on this page, and you’ll be directed to my website.

Custom deck and porch contractor Massachusetts & Rhode IslandTechnorati Profile

Mahogany decking comes in a wide-range of species and color, supplied by many countries around the globe. However, not all mahogany decking are alike. The type of mahogany decking you’ll find most here in Massachusetts and in the rest of the country will refer to — American Mahogany. American Mahogany has a very deep rich reddish color that most have come to enjoy, especially in New England where I’ve constructed many of these decks. American mahogany decking comes from primarily Mexico, Central and South America

Generally, Mahogany decking has been viewed by many contractors and homeowners for its decking being a hard and highly durable. Since mahogany decking is a harder more dense wood, it has the tendency not to buckle, split or warp. Also, please note Mahogany decking will be a little more expensive than pressure-treated decking, however it’s well worth the investment and looks great to home-buyers and is durable.

Fastening materials for securing Mahogany decking

As a deck contractor here in Ma., I prefer using stainless steel screws for decking installations. Other types of fasteners may not penetrate to well or not hold up to well. However, pre-drilling holes is mandatory if not using a nail gun. Even with stainless steel nails, they will bend trying to simply nail them into the mahogany wood decking. I found with using stainless steel hex head screws, you’ll ensure the maximum bond between your decking and the frame.

When installing the mahogany wood decking, I found it aesthetically most attractive to create a picture-frame on the outside perimeter of the deck surface using long Mahogany decking boards.

Once the outer frame is installed, then the main Mahogany decking boards can be simply installed within this outer framework. The result is a cleaner line when viewed from a distance or standing on the deck itself.

Regarding the mahogany railing system, screws and bolts should be used exclusively as the material use in this part of the deck is typically thicker and requires more rigidity.

Staining or Sealing Mahogany Wood Decking

Mahogany wood decking takes paint and stain well, however I have preferred to apply a clear sealer. The clear sealer enables the natural red color of the Mahogany decking to shine through, while still providing a layer of protection from the environment. Typically I re-apply the clear sealer every year to continue to preserve the color. If you do not, the Mahogany will bleach out.

If you live in Massachusetts or Rhode Island and in need of a deck contractor, feel free to click on any highlighted link on this page, and you’ll be directed to my website.

Custom deck and porch contractor Massachusetts & Rhode IslandTechnorati Profile

When building a deck onto your home it is crucial to properly install deck flashing above, behind and below the deck ledger boards. As a home improvement contractor, I’ve personally seen what can happen to a deck that never had deck flashing or improperly installed deck flashing. Deck flashing protects water from seeping behind the deck ledger board and from becoming trapped in between your ledger board and home wall sheathing. If water becomes trapped between your deck ledger board and home sheathing, rot, mildew problems will quickly grow into a big problem in the future. I’ve seen decks that didn’t have flashing or improperly installed flashing begin to detach from the home — that’s not the kind of deck I want to have BBQ party on!

What is deck flashing?

Deck flashing is a thin piece of metal that comes in rolls of length, ranging from 8″ inches by 50′ feet and upto 24″ inches by 50′ feet. The most common types of deck flashing you will find at any local home center is Copper, Aluminum and Vinyl deck flashing.

What kind of deck flashing should you use?

I prefer to use Copper for any type of deck construction I do – you can a also use vinyl flashing. In recent times you could use Aluminum flashing until they changed the way they preserved pressure-treated lumber. The manufactures of pressure-treated decking and lumber used to infuse the wood with a chemical preservative called “chromated copper arsenate (CCA) for protecting the wood. They have since banned that procedure for a much more safer process of wood preserver alkaline copper quat ( ACQ ). Although the new pressure-treated lumber is much safer and less harmful to the environment, the chemicals in the pressure-treated lumber are more corrosive to the hardware.

When building a new deck using

pressure-treated lumber as your framing members and supports, be sure to install copper roll flashing behind the ledger, and also use hot dipped galvanized nails and hardware for your structural fasteners. Hot dipped galvanized joist hangers, nails, lagbolts and post brackets are resistant to the corrosion, and the chemical reaction caused from ACQ.

How to install deck flashing?

It’s actually quite simple to install deck flashing. For example, if you’re building a deck using 2×8 as your ledger board you will want to purchase a roll of copper flashing to the width of 12″ inches. Just follow the steps below.

• If you’re building a deck to the width of 10′ feet, you want to cut the copper to the length 10′4″ this will allow plenty of room to run past each end of your deck ledger board.
• Next, remove the first coarse of siding so you can install the deck flashing up and underneath the first coarse of siding.
• Followed by tacking the roll of deck flashing up with staples or roofing nails, then proceed to install your deck ledger board. Have a look at my photo below for a better idea.

If you look closely, you’ll notice

how I like to take extra precaution when installing deck flashing behind the deck ledger board. You’ll notice how I will use grace ice and water shield protectant to run just below the top of the copper deck flashing. Or let me rephrase that, you’ll notice the copper deck flashing running up and behind the grace ice and water shield ( the black stuff above the copper flashing ).

Another view from the underside of the deck, to give a better idea of how the deck flashing should run smooth across the underside of your deck

Here is another picture view of how you want to run your deck flashing outwards away from the deck ledger board. This way here, no water can penetrate from the sides of your deck ledger board.

Here’s what the deck frame looked like as I was building it.

Here’s what the deck looked like with the pre-primed pine wrapped around the deck! I’ve been constructing all of these decks for this big sub-division, among other projects for this builder.

And finally, the composite deck construction using composite decking, wrapped in pine, with the proper deck flashing ledger board technique.

• Will this deck be primarily for entertaining?

• Will this deck just be an entry way to my home?

• Will this deck just be a place to put a few chairs, table and a grill?

Keeping that in mind, you’ll next want to carefully consider what size of a deck you want to build and the design of the deck, remember you’ll be living with this deck for a long time – think it through. Here are some helpful tips to decide how big of a deck to build.


What size deck?

• What size decks are consistent with the neighborhood I live in?

When thinking this part through, you don’t necessarily need to have the biggest deck in your neighborhood, but you don’t want the smallest one either. There is no set rule on how big of a deck you can build, but, you don’t want it to become overpowering either.

Test your deck planning Ideas

To test your ideas, layout all of the furniture in the area you plan to have on your deck. Next, grab your garden hose and lay it around the area you intend to occupy -giving yourself enough room to freely move about, followed by measuring out that area once satisfied. The most common mistake people make is building a deck too small.

Deck planning Tip:

Whenever possible, plan the size of your deck to even lengths, i.e 10×10 or 10×12 –don’t build a 10.5 x 11.5 unless you have no choice or that’s what you want. Either way, you’ll have to buy standard lumber lengths anyway, and there’s no point in wasting that material when you could have a larger deck for the same amount of money.

Shape and Decking Patterns

A deck can be any shape you want, and in fact, simple changes like an angled corner or a 45 degree herring-bone decking pattern can dress up a house. You can also add style by wrapping the deck with a pine skirt, adding built-in benches, integrating a privacy fence or screen on one side, or even adding an overhead sunset awning.

Click on this link here: For a Massachusetts or Rhode Island Deck Quote

Dear Mike,

I have a question about the new decking I’ve installed for my new deck. Before I go ahead and stain my pressure-treated deck, how do I remove the writing from the pressure-treated lumber? Please help!!!

Kathy,

Seattle, Washington

Dear Kathy,

Thank you for writing in with your concerns about your new deck, I hope that I can answer your question to your satisfaction. First off, let me explain to you the story behind the writing that we find on new pressure-treated decking, or any new type of wood you see in your local home center.

Lumber Grade Stamp

The writing you find on all types of wood decking, is called a “manufactures stamp.” Grade Stamp (lumber) – A grade stamp shows: (1) The species of the wood or species group; (2) the grade number; (3) the registered symbol of the certified agency; (4) the mill identification number; (5) the seasoned condition of the wood. In the illustration, this grade stamp states that the lumber is certified by the Western Wood Products Association, from Mill 12 (which can be found in the WWPA membership directory); is from a coniferous tree (also known as softwood – Spruce-Pine-Fir); was graded according to National Lumber Grades Authority rules; is kiln–dried and heat treated (19 percent or less moisture content); and is of standard grade. Have a look at the Illustration below for a better idea.

How do I remove the grade stamp?

Removing the manufactures grade stamp from pressure treated decking or any type of lumber, isn’t to difficult at all. Now, with the right tools you can tackle this simple task of removing the stamp.

Tools needed to complete the task:

1. Orbital sander

3. 80 grit sand paper

3. A little bit of elbow grease
Deck sanding tips:

Before you go ahead and start sanding, you need to know the correct procedures so you don’t end up with a bare, or light spot on your decking. I would hate for you to stain your deck and then always see that one spot shine through the stain, and look awkward!


1. The first thing you want to do before removing the stamp from your decking, is to practice on a scrap piece of decking. Grab a spare piece of decking 2-4′ feet in length and practice sanding before you tackle the final product.

2. Use these sanding techniques. You want to move in a back and fourth motion. For example, if the spot on your deck is roughly 4″ inches by 4″ inches, start in the center and move the sander gracefully 1′ foot past the center in both directions. The reason for sanding more than just the spot on your deck, is because you want to blend the spot you sand into the decking to avoid having a “bald-spot” on your decking. This way here, it blends in with the rest of your decking.

4. Once you have the spots removed, simply start sanding the entire deck. This way you’ll have an evenly sanded deck before you go ahead with the staining process.

5. You’re done! Kick back and enjoy your deck..

Kathy, I hope that I’ve answered all of your questions regarding your deck problem. If you have any other questions, feel free to ask away! And to others out there, if you feel this task isn’t something you can handle on your own — hire us to do the job for you!

Custom decks & porch contractors MA, RI

As a custom deck builder and home improvement contractor in Massachusetts, I’m often regularly asked these kind of questions once I’ve built their pressure-treated deck. So I will do my best to answer the most common question I can think of now. Understand this before I move on, staining your treated decking involves the same process as untreated-decking — the main thing is that the wood is clean and dry from any moisture or dirt.

cabots deck stain

Can I stain pressure treated lumber?

Yes, you can stain pressure-treated lumber with the one exception, that the decking has completely dried out and has been clean of any and all dirt.

How long should I wait to stain pressure-treated lumber and why do I have to wait?

The process begins at the lumber yard factories and treatment plants. The pressure-treated lumber goes through a process of using a water-based solution that carries the treatment of chemicals into the fibers of the wood while under pressure; this leaves the wood wet.

What if I decide to stain the pressure-treated decking or wood before it’s dry – are there any consequences?

If you were to go ahead and stain or paint the decking before it dries, you’ll end up with bubbles -or- blisters forming on your deck. Also keep in mind, you’ll end up locking in moisture inside of the wood creating fungus or rot to take hold and destroy the wood.

What are the time tables for staining the deck, how long should I wait?

It all depends on what region of the country you live in. If you live in a hot sunny state like Arizona, give it a few weeks and it will more than likely be dry. However, here in Massachusetts it all depends on what season your deck is being constructed in. In the spring and summer months here in MA. I would wait 30-60 days before I would treat your deck with stain.

What kind of stain should I use for pressure treated lumber?

There are stains on the market today. My favorite type of stain would be Cabot stain, it holds up to the rough seasons we see here in Massachusetts the best. Many people believe Thompsons is the best, I completely disagree –they only have the best marketing! Just read the backs of the can and follow their directions…

How should I stain pressure treated lumber? Or, how should I apply the stain?

Read the can because it varies with some stains but most stains can be applied with a brush, sprayer, or sponge. You will probably find a sprayer to be the easiest method.

Should I stain pressure treated lumber yearly?

Yes! If your looking to preserve the deck, porch, patio for years to come stain your deck annually.

My final thoughts:

Staining pressure treated lumber is not rocket science. In fact, there is nothing remotely complicated about it but it does take time and if you don’t do it properly, you’ll mess it all up. If I did not make this point obvious enough above then let me say it again here:

Treated wood must be dry before you stain or paint it.

Enjoy your project. Wear gloves. Wear goggles. Be careful with tools. Work in ventilated areas.

Feel free to comment on my page, I’ll answer your questions to the best of my ability. And if you live in Massachusetts or Rhode Island and in the market for a new deck or porch, visit my home page – the link will be highlighted below.

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