I have recently been working in my garage, repairing the garage floor, and setting up a new workstation, and when I came to get the levels right I noticed the floor was sloped in one direction, and I wondered why this was the case,
Was it a mistake or poor building work or a design requirement?
I took some time to find out and bought the information together to share with you in this post:
Garage floors are sloped to drain water and fluids out away from the house. Building regulations state garage floors should slope towards an outer door or a suitable drain and should have a fall of up to 12.5mm (1/2″) per foot to help prevent water ingress and damage.
I was glad then to find out that my garage floor was not laid by poorly skilled builders but sloped for a reason. I then looked at what the gradient should be, as there are different requirements which I go through in more detail below.
Keep reading to find out how if your garage floor is up to the current building code.
Should garage floors be sloped?
Garage floors should be sloped to meet building regulations, which state that to prevent fluids like split fuel or water from entering your house, the garage floor should fall away to an outer door or a suitable drain point.
For many of us, water tanks, boilers, and washing machines are located in the garage all of which contain or use water and if they ever leak, then a floor with no fall will allow water to pool and potentially leak into your home causing water damage to floor surfaces, timbers, and electrical circuits.
In temperate climates where rainfall is common and areas that are subjected to cold winter weather, runoff and melting snow can also be a problem, and a garage floor that slopes towards the door and will keep excess rain and meltwater away from the interior of your house.
Building codes and regulations will dictate the requirements needed to protect your home from ingress of water or split fluids and different areas will have different rules, which will take into account weather conditions, temperature changes, rainfall, the local water table levels, ground conditions, and soil types.
What slope should my garage floor be?
The degree of slope on garage floors will depend on the environmental factors listed previously and will be defined by building control for your local area,
Garage floors will have a slope or ‘Fall’ between 1/8″ per foot and 1/2″ per foot, the fall is made towards the outside of the property. This is enough to prevent liquid pooling on the surface or running towards the interior of the house.
The slope of a floor is also known as the ‘Fall’, Gradient or ‘Pitch’. If your property is susceptible to cold weather with icy or snowy conditions or if you are on a sloped building plot, perhaps your house is on the side of a hill, then your garage floor will require a steeper fall to prevent water ingress into your home.
A fall of 1/2″ per foot would equate to a drop of 10″ on a 20-foot long garage, this might seem a lot but you probably won’t notice when walking around normally.
Which direction should a garage floor Slope?
Most homes with integrated garage floors will be sloped in one direction usually running downwards away from the property towards the main garage door.
Detached or standalone garage buildings will typically be sloped in one direction towards the main door. the location of the garage in relation to the house would dictate which way the garage door faces, so that water runs away from the property.
Garage floors with internal drain points will typically have a low point where the mouth of the drain is set into the floor and the garage floor will be sloped towards this point.
The slope of the floor is usually set from each corner of the structure to even out the fall this makes laying the floor more complex than a single slope as there are compound angles involved.
Drains inset into garage floors need to be properly designed and constructed correctly by the builder or contractor and will be included on any plans drawn up by architects plans to be used by builders.
Drains should be connected to the main drainage system so that the water can flow away correctly.
Any fluids that are non-biodegradable or hazardous to the water system should be dealt with before they reach the drain and enter the watercourse.
This article was written by: Richard Quinton – The DIY Help Desk Owner, Engineer & technical specialist.
Richard is one of the key partners in The DIY Help Desk team. He is a qualified Engineer, writer, and publisher, educated to Master’s level. He is a keen advocate of DIY and home improvements.
Richard enjoys helping others to learn new skills and reach their goals and believes that passing his knowledge and experience on through his writing is an effective way to positively impact the lifestyles and well-being of others on a larger scale.