Home sunlight
How to know where shadows will fall on my house
The shadows around a house move by the hour and stretch through the winter. A wall with clear spring mornings can sit in shade from December to February, and a neighbour’s roof may only matter for two hours a day.
By SunCast team Last updated: October 14, 2026
Short answer
Open the property on SunCast’s 3D map and step through the day for the date you care about to see shadows from mapped buildings. On a slope, turn on Terrain Shadows. Then stand at the window, patio or garden bed and use the AR Sun Tracker to check what the map cannot show, such as trees and fences.
How far a neighbour’s shadow reaches
In Chicago on 21 December the sun reaches only 24.7° at 11:49 CST. A neighbouring two-storey house 8 m tall casts a 17.4 m shadow at noon, and by 15:00 that shadow is about 40 m long and points north-east. On 21 June the same house casts a 2.7 m noon shadow (calculated with SunCast’s sun calculator).
So a garden or ground-floor room that looks fine at a summer viewing can spend most of a winter afternoon in a neighbour’s shadow. The rooms, patio, roof and garden beds you use most are the places to test.
Checking house shadows in SunCast
1. Pick the spot that matters
Choose the window, garden bed, patio, roof plane or driveway you care about. Checking the whole plot at once hides the answer.
2. Step through the day on the 3D map
Find the property on the 3D map, set the date and move the time from sunrise to sunset. Note the hours when a neighbouring building’s shadow covers your spot.
3. Add terrain on sloping sites
If the house sits below a hill or ridge, use Terrain Shadows to see when the slope itself puts the property in shade.
4. Check trees and fences in AR
Stand at the spot and open the AR Sun Tracker. Where the sun path passes behind a tree, hedge or fence, you will lose direct sun that the map does not show.
5. Repeat for December
Winter gives the longest shadows. If the spot still gets the sun you need on 21 December, the rest of the year is easier to trust.
SunCast features for house shadows
You can check any hour and season from the map without waiting for it, then confirm the details on site.
| SunCast feature | How it helps |
|---|---|
| 3D shadow map | Shadows from mapped buildings around the property for any date and time. |
| Terrain Shadows | Shadows cast by hills, ridges and valleys as the sun moves across the day. |
| AR Sun Tracker | The sun path for any date over the camera view from a window, wall or patio. |
| Sun Times & Position Data | Azimuth, elevation and shadow ratio. Multiply an object’s height by the shadow ratio to get its shadow length. |
Things people miss
Only checking the front of the house
The light that matters most may be in the back garden, a bedroom, an office or on the roof.
Forgetting trees
Trees in leaf can shade a patio in summer even when the building shadows look clear.
Assuming today is typical
Today’s shadow can be a poor guide if the season is about to change.
Limits
The 3D map casts shadows from mapped building shapes and terrain; trees, fences and recent extensions generally are not mapped. For legal disputes, measured daylight reports, solar engineering or planning evidence, use the required professional process.
Check it in SunCast
Checking the light around a home? Open it on SunCast’s 3D map, step through a December day, then confirm trees and fences with the AR view.
Frequently asked questions
How can I tell if a neighbor will block my sun?
Find the neighbour’s building on SunCast’s 3D map and step through the hours and months that matter. To estimate by hand, multiply the building’s height by the sun’s shadow ratio for that time and compare the result with the distance to your window or garden.
Do house shadows change much by season?
Yes. In Chicago an 8 m house casts a 17.4 m noon shadow on 21 December and a 2.7 m one on 21 June. Low winter sun creates far longer shadows than high summer sun.
Can I check shadows before buying a house?
Yes. Check the address on the 3D map before the viewing, then confirm from the rooms and garden with the AR view during the visit.
