Trim a slab

Expansion Joints

Trim-A-Slab is a replacement for rotted and old wood typically found between slabs in driveways and sidewalks. This wood was used during the slab construction, and is part of the ‘formwork’ used to define the size and shape of the slab. Once the cement had cured, it remained to accommodate expansion and contraction of the slab as it is heated in summer and cooled in winter. This wood then functions as an ‘expansion joint’.

Typical Slab Construction

The problem is what makes good formwork does not necessarily make a good expansion joint.  The elements conspire to attack and destroy the wood, even if it was a rot resistant variety or pressure-treated to resist rot.  Moisture allows bacteria to attack and break it down, movements open gaps which allow dirt and roots in, and eventually, the formwork looks a lot more like potting soil than wood.

What wooden expansion joints are faced with

Unless treated with weed-killers, your driveway can easily look like the one pictured below.  Of course, chemical weed-killers are also undesirable, as driveways are almost always very close to storm drains.  The best way to keep chemicals out of your local watershed and fisheries is not to use them at all.

A driveway gone bad

 

Trim-A-Slab

 

Trim-A-Slab is made from a rubber-like material that flexes and holds itself into the gap between concrete slabs.    It is immune to rot, moves with slab expansion and contraction, and is not affected by moisture.  It provides a redundant barrier to weed growth, and most importantly, does not trap dirt and debris like wood and other less flexible products.  It will make your driveway easier to keep clean.

Trim-A-Slab

Trim-A-Slabs patent pending design is intended for slabs with radius (rounded) edges, and will fit and stay just below the surface without any special preparation   The exposed surface is slightly recessed, and is resistant to damage from foot and auto traffic.

Installed Trim-A-Slab

The clean, finished appearance is something your family and your neighbors will notice right away.  It’s virtually maintenance free, and in case you need to run wires across your driveway for Christmas lights or an irrigation system, Trim-A-Slab can be removed and re-installed, no problem.

 Trim-a-slab comes in black or grey.  Choose black for the lowest maintenance and an accented appearance, choose grey to blend in.  Grey will show tire marks after a while, but it cleans up easily with soap and water.  Both are guaranteed for 5 years, so whichever look you prefer, you can be sure it will last.

 Trim-A-Slab is available in 50 ft rolls, which only weigh about 10 pounds each, so if you do want to install yourself, it’s easy to handle.  Visit the installation page for all you need to know about installing Trim-A-Slab.  If you aren’t the do-it-yourself type, then visit the distributor’s page for a list of installers, who will take care of the whole job for you.

Cost Comparison

 

When it comes to expansion joint repair, there are a few options to consider.  You can replace the wood with new wood, replace it with caulk, or replace it with a filler strip.  Of these options, wood is clearly the worst.  It is the hardest to fit back into the space, and there is no easy way to secure it.  Any warping tending to lift it out of the joint will create a protruding trip hazard.  All the same problems explained above with new wood remain as well, so weeds will establish themselves in the cracks, and in a few years the process will have to be repeated

 The next thing to consider is the caulk-like repair.  This method has a few issues as well.  The material will fill the void space completely, which is good, but any subsequent caulk shrinkage or movement of the slab to open the joint will create a vertical crack.  This crack then fills with dirt, debris, and finally weeds.  The caulk-like fillers simply don’t have enough compliance to fill an expanding gap. 

These materials also must be installed with some planning and skill.  The depth of the evacuated joint must be closely controlled in order to be able to correctly estimate the amount of stuff needed to fill the joint.  This can be done by back-filling the joint with sand, or by installing a filler strip which is pushed down to the desired depth.  The filler strip is fairly easy to use, but the finished expansion joint is actually poorly supported, and can collapse down into the joint over time or due to foot or wheeled traffic.  Lastly, the caulk-based repairs are a viscous sticky liquid which must cure.  This means it must be installed carefully, and in a controlled manner to get a nice end product.  The following instructions are from a tube of name-brand concrete and mortar filler and sealant:

Apply in temperatures over 40 F

Do not apply when rain or freezing temperatures are forecast

Joint should not exceed ½” wide by ½” deep

Allow to cure for 24 hours before direct exposure to water

Completely dry in 7-14 days

Caulk Fill

The best method is to re-fill the gap with a compliant filler strip.  The more compliant the strip, the greater the range of motion that the joint can have without allowing dirt and weeds to accumulate.  There are only a few choices in using this method, which is why Trim-A-Slab was invented.  The other filler-type repairs which we have found to date are both Texas companies, and are vinyl products which are considerably more expensive than Trim-A-Slab.  These products also have application instructions which require significantly more preparation than Trim-A-Slab.  The depth of the joint cavity must be controlled, and it is recommended to fill with sand prior to installing their products.  While these products are also ’removeable’, their installation guidelines include use of a hammer, so just how removeable are they?

 We do recommend these products if your slab does not have a radius (rounded) edge, as they are the best option available, and they can be mixed with Trim-A-Slab in the grey color if you have some radius edges, and some sharp corner edges.