Many people opt to use paving slabs for their shed base rather than going the full concrete slab route. People who have built walkways or driveways with slabs often have some left over. Sometimes there are enough left to build a foundation for a small shed.
Paving slabs are especially good for smaller sheds and sheds that will stand on level ground. They provide a level, sturdy base for lightweight sheds. You should, however, check with your local building code enforcement authority before planning a paving slab foundation.
Many localities require building permits for all but the smallest sized sheds, even if they are purchased pre-built. Your local code enforcement authority may not require you to have a building permit for your shed, but may require one for the foundation, or at least have restrictions on the type of foundation they permit.
If you plan to run any utilities to your shed, such as electricity, you’ll need a permit no matter the shed size. You may be able to find much of the information you need on your municipality’s website.
In addition, even if you don’t need a building permit, code enforcement may have some restrictions on the types of foundation you can use for your shed, so you do need to check with them before making any definite plans or purchasing anything. Local weather conditions may play a part.
In colder climates where frost heave is a problem, a paving slab foundation may have problems with moving soil cracking the cement base holding your slabs. If you don’t secure the slabs with cement, your foundation idea may be deemed to be not solid enough for building codes.
In areas subject to frequent high winds, you may also run into problems with paving slabs being ruled not to be a solid enough foundation, especially if your area requires you to tie down your shed to prevent wind damage.
Be sure to find out all the rules and regulations about using paving slabs for a shed base before you start doing anything towards building or buying a shed except for getting your proposed building plans. You’ll need detailed plans for both the building and the location to submit for a building permit and to get location approval.
Zoning regulations are a wholly different subject, restricting the location of your shed as to distance from the property lines or other buildings, distance to underground or overhead utilities, the height of the roof, soil types, or even potential flooding conditions of your proposed site.
If you live in an area governed by an HOA, you may run into additional restrictions, such as keeping your shed from being visible from the street or the type of shed you are permitted to have.
Can You Use Pavers for a Shed Floor?
Besides using the paving slabs for the shed base, people who are buying prefab sheds sometimes use the paving slabs as the flooring as well as the foundation. Many plastic sheds, for instance, don’t come with a built-in floor, although they usually have some kind of built-in slots or grooves meant to hold flooring.
If you are planning on buying a pre-built shed and have some pavers around, you can save money by building a paving stone foundation and flooring combination, then buying a shed without a floor.
Is a Paver Base Better Than Gravel?
A paving stone base can be sturdier than a plain gravel base, especially if you set your paving slabs in cement. While gravel is usually the cheapest foundation you can have, it’s not suited to all types of yard terrain or soil conditions. Even your soil type must be taken into consideration when planning your foundation.
You will still need gravel underneath and around your base to facilitate drainage. Another good idea is to set your shed on skids or heavy beams to raise it up a few inches. This allows for airflow underneath your shed and protects the underside from moisture seeping up from the ground or heavy rain that causes rainwater to sweep against and around your shed.
What is the Best Material to Put Under Pavers?
You’ll need to plan for having four to six inches of gravel underneath your shed pavers. This helps with drainage as well as keeping the ground stable. Laying your pavers right on the soil or on sand will not prevent the soil from eventually shifting or eroding underneath your pavers. Your pavers may even sink over time without the gravel base.
Mark out your proposed site with stakes, making sure that each corner is at a 90-degree angle. You can then tie strings to your stakes or use spray paint to mark a line on the ground to outline your site.
Dig up your site to a depth of about six inches. Take out any roots or rocks from your site. You’ll need to then tamp the soil down firmly. There are long-handled tamping tools available with heavy, square or rectangular bases. If you are planning on a sizeable shed, you can rent a power tamper. Keep in mind that you’ll also need to tamp down the gravel more than once as you lay it.
Fill the area you dug with gravel. Fill it just two inches at a time, tamping down the layer before pouring more. This will give you a much firmer foundation than trying to tamp down six inches of gravel all at once. It will also eliminate far more airspace which may allow rainwater to hang around underneath your paving slabs.
Four to six inches is required, with six being preferred. You should get rougher-type gravel such as roadbed gravel or crushed stone. This type has sharper edges that tamp down more firmly. Avoid pea gravel or any gravel with rounded edges.
What to Put Under Pavers to Prevent Weeds?
Heavy landscaping fabric underneath your gravel sub-base will keep weeds from growing up through the gravel and trying to poke up between the pavers. If you can, try to find a commercial-grade fabric. The heavier the fabric, the less likely you will get tears in it when you are laying and tamping your gravel. Even if you set your pavers in cement, over time, small cracks may develop in the cement between the pavers, and weeds will take advantage of these without the fabric.
Do I Need a Vapor Barrier Under the Pavers?
You really don’t need a vapor barrier under paving slabs for a shed base. Your gravel sub-base will take care of drainage. There are situations where you will want to have a vapor barrier, check out my article Do I Need a Vapor Barrier Under My Shed? for more information.
How to Install a Paving Stone Base
Mix one-part dry cement to eight parts dry sand for your cement. It’s a good idea to measure out how much water you think you’ll need, then put about half that into your cement mixer or wheelbarrow first, then add the dry mixture. Add water gradually and keep stirring. Keep in mind that you may not need all the water you thought you did.
Spread a two-inch layer of the mixture right onto the gravel base. Smooth it out as you go. Once you have it laid and smoothed out, compact it down, making sure that the surface is level as you go along.
A chalk line will help you line up the pavers. Start with a corner. You’ll need a rubber mallet to keep the pavers level. Level each one after you lay it. Keep them about 1/4 inch apart on all sides. You may have to cut some at the edges to make your rectangle. Add a border edging, then stake the border to keep everything in place.
Spread a mixture of dry sand and cement over the pavers, with the cement and sand mixed in the same ratio as before. A broom is good both for spreading the mixture and getting it tamped in between the stones. Make sure you get all the gaps firmly filled, then sweep all the excess off the surface.
Dampen the entire surface using a fine spray so that you don’t dislodge any cement mixture. The water will cause the cement between the stones to harden. The foundation will need to cure at least 24 hours before you add the shed itself or start building it.
Can I Anchor a Shed into Pavers?
You can anchor your shed into your paving stones if you made a concrete base for the pavers underneath. Paving stones by themselves will not be enough to anchor your shed, even the larger sizes. If you can pick up your pavers, so can a hard wind, especially if it has something to push against, such as your shed wall.
Be sure to check with your building code enforcement office first. They may require a more sturdy method of anchoring your shed or specify how thick the concrete base must be in order to anchor your shed to it. They may require additional attachments such as using ground anchors set in concrete.
In fact, it’s probably less work to just use ground anchors to begin with. Concrete piers set into the ground off the corners of the shed with attachments set into the concrete for holding straps or cables are much more sturdy and foolproof than trying to attach your shed to the concrete base, especially if you have to drill through the paving stones themselves.
Check with your code enforcement, as they may have regulations as to how many anchors you will need for the size shed you have.
If attaching your shed through the stones to the concrete is permitted, you’ll need to use masonry bolts. Plan for bolts long enough to go at least as deep into the concrete as through the sill plate while also going through your paving stones. Another method would be to attach anchor plates to the sides of your concrete base to hold your sill plates.
How to Anchor a Shed into Concrete Pavers
You’ll need concrete expansion anchors for this. They are designed for use in concrete and expand once they are drilled into place. You’ll also need a masonry drill to get through the pavers without cracking or breaking them.
Pavers are prone to cracking when you’re trying to attach these bolts. You’ll need to drill pilot holes through both the pavers and concrete base to attach the bolts and hold the shed.
Place your sill plates on the base and mark out the places where you want your anchors. If you’re buying a pre-built shed, you can install the anchors into your base first, then drill holes in your shed base frame to line up with them. It would be much easier to drill it all at one time.
What you’ll do is use a hammer drill with a masonry or concrete bit to drill down through the sill plates, the paving stones, and the concrete base. Clean out the holes as well as possible, using compressed air if you have it. Thread the nut onto the top of the anchor bolt. This will protect the threads as you hammer them into the holes. Leave enough at the top for your bolt and a bit more.
To anchor your shed to paving slabs, you really need a concrete base that’s at least three inches thick. This is because you’ll actually be anchoring your shed to the concrete, not the pavers. The pavers will just be something you have to drill through to get to the actual anchoring material.
Most people who want to use pavers as the shed base do so because they don’t want to go through all the work and expense involved in pouring a concrete slab, so if you have to have a slab for a proper anchor anyway, that takes away at least one reason to use paving stones. You’ll be much better off using concrete piers to anchor your shed rather than connecting it through paving stones. You’ll probably make code enforcement a lot happier as well. If you need another option check out my article What’s The Best Shed Foundation Option For You?
Using paving slabs, especially the thicker ones, is an economical and fairly easy way to form a shed foundation. Paving stones also make an attractive and uncommon shed floor, if you need to use it that way. Just check your local regulations first to see what you are permitted to do and what adjustments you may need to make in your plans, and you should be fine. You knew you kept those leftover paving stones for a reason, didn’t you?