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When you measure for either a replacement door or a door for a new garage you may not yet have decided on the type of garage door you want and where it is going to actually fit. If this is the case then you are best to measure everything including inside garage dimensions so you can discuss all possibilities, pros and cons.
If you are replacing an existing up and over garage door and it is on a good solid timber frame that you are leaving in place then you can just measure the internal dimensions of this frame but we still need to know the frame width as some newer doors require so much more width than certain older up and over garage doors do for the operating mechanisms.
A good start is our online survey form. Download this, print it out take the measurements and use it in your discussions .
Obviously we need the width and height of the actual opening itself but all the internal sideroom, headroom and depth is also needed for many door types such as roller and sectional doors. Also check if the opening is square if possible with a good level floor.
See our tips on 'measuring garage doors'