there are exposed roots under my cedar tree and I am not sure if I can snip them as I think they are a trip hazard and will also damage my lawn mower. The cedar tree has several stems and also goes to just above the roof of my bungalow. It is maybe 30 years old I think
Dealing with roots from trees can be a challenge, so Toronto Master Gardeners is glad that you have thought to inquire about your problem before pulling out your saw. It is true that removing too large, or too many, roots could affect the tree’s water and nutrient flow and compromise its stability, so arming yourself with information beforehand is wise.
From your photo, it looks like the roots from your cedar are not very large. Depending on the size of the lawn, there might be an opportunity to top dress it to level the area so it can be seeded with grass, and maintained without having to cut roots. However if the area is too large, cutting the roots might be the most efficient.
According to many arborists, one should avoid pruning roots more than 2 inches wide. Furthermore, do not remove more than 15% of the surface roots at one time: it is recommended to observe the tree for a year or two, to see if pruning has caused any adverse effects. To prepare for the removal, dig a hole all the way around the root until it is completely exposed. Ideally use a pruning saw to cut the root cleanly, remove it and refill the hole with soil from the same area afterwards. The best time to do this is now, spring, before our temperatures rise significantly.
Lastly, we recommend keeping an eye on your cedar this summer. If you notice any signs of stress, we suggest contacting a certified arborist, which you can find here https://www.isaontario.com/hire-a-certified-arborist/