A properly fitted threshold very seldom needs adjusting but occasionally problems arise that make it necessary.
The most common problem that requires threshold adjustment is water penetration that causes the threshold to swell or distort so that it comes into contact with the door. A less common problem is a distortion in the floor that can be caused by the cumulative effect of heavy furniture or simple settlement in a relatively new house. A much less common problem arises when a door is too heavy for the frame in which it is fitted and starts to sag.
A heavy door can only continue to be heavy so trying to cure the problem by adjusting the threshold can be a terrible waste of time.
A threshold that has been distorted by water penetration or dampness will often only give intermittent problems when the air is moist or when more water penetrates. Adjusting this type of threshold and curing the problem is relatively simple.
Wait for the Threshold to Dry
Since the problem does not exist when the threshold is dry, you must wait for it to dry out.
Seal the Threshold
Once it is dry it is necessary to seal the threshold so that moisture and water can no longer affect it. The best way to do this is to use a proprietary sealant or to apply a good quality varnish. If it is possible, the threshold should be taken up off the floor so that the sealant or varnish can be applied to all surfaces and the threshold re-fitted.
A threshold that needs adjustment because the floor is distorted is also usually a simple matter to fix – it depends upon how much the movement of the door is restricted.
Find the Rubbing Point
Use a colored chalk and color the threshold and then close the door. The chalk will be scraped where the door makes contact with the threshold and this will show you where the adjustment needs to be made.
Little by Little
As you see where the door and the threshold are making contact you can take small shavings off the threshold at these points. Sometimes the degree of obstruction is so small that the application of a coarse sand paper is enough to cure it. Don’t give in to the temptation to shave too much off the threshold.
Once you have eased the threshold so that the door swings freely you will need to clean up the threshold and treat any exposed wood with the same finish as it had before. If necessary, you can use a fine glass paper and prepare the threshold for a new coat or two.
Although adjusting a threshold is easy, it is important to realise that if the threshold has been fitted properly and the problem is a new one, you need to ensure that there isn’t a more serious problem of which the threshold is only a symptom.