Lego pieces. That’s what blocking is, right? Unfortunately, not at all. Although it does have to do with construction and structural integrity, its proper place is in the realms of necessity. Blocking is an essential part of any constructed building and applies to many different trades and portions of the construction process. The necessity in our realm applies to that which directly affects drapery installation.


Wall Mounted

To begin, though, let’s consider this theoretically. Since we aren’t all engineers or construction science specialists, let’s ask the question; what is blocking in layman’s terms. Blocking is support within a wall or ceiling that holds heavy items. Think about hanging a picture or shelf in your home or apartment. When you get ready to insert the nail, what are you hoping to hit on the other side of the drywall? A stud, because a stud will hold the weight of the picture or shelf. The stud, while being specific to walls, acts as the blocking. It fits our definition of ‘support within a wall' (in this case) that holds a heavy item, although continuous blocking is required for drapery treatments, due to our 24" support requirement. This is to say that when installing into a wall we do not simply go and find the studs. We must support drapery track every 24" regardless of studs and therefore continuous blocking should be in place directly behind the sheet rock.

Wall MT- Drapes.png

 Ceiling Mounted

That being said, the majority of drapery hardware is installed in the ceiling. While studs are always in walls no matter what you are building, ceiling blocking cannot be taken for granted as a standard practice in the construction of a ceiling. So what do you do? If you were to install drapery hardware into the ceiling without blocking it would pull straight through the sheet rock. Therefore the necessity of good blocking is a must for the guarantee of guest safety.

Ceiling blocking needs to be installed wherever drapery track will be installed. The blocking needs to be at least a 3/8" thick located directly behind the ceiling surface. It needs to span the width of the widest treatment, and needs to have a depth from window wall out into the room corresponding with the furthest treatment from the window wall. The depth of the blocking is an important point to note and can be confusing. The key to remembering is multiples of 3. All drapery treatments must be 3” apart. If you add up the number of treatments you will have in a specific room (over drape – 1, sheer – 2, cornice – 3) and multiple by 3 you will solve for the distance from window wall where the furthest treatment will be installed and therefore solve for the depth that blocking is needed (9" for 3 treatments). See the image below for details of the depth of blocking and read our blog “How Much Space Needs to Exist Between Treatments?” for a better understanding of why there is so much spacing between treatments.

Ceiling Mount Blocking

The blocking must be supported to a level which provides structural support for the weight which will hang from the blocking, and again the location (either wall or ceiling) will be determined by the specifications.


In order to support a Roller shade, the concept in the same. Blocking will need to be installed wherever the shades will be mounted. Roller shades are slightly different because blocking is only necessary where the roller shade brackets are located and they require two sides of blocking instead of one like draperies (i.e. on the wall closest to the window and directly above the roller shade). This will ensure that the shade is securely mounted.

Inside Mounted

For an inside mounted roller shade, the blocking will need to be above and level with the window inside the window frame.

Inside Mount-Shades-05.png

Outside Mounted

Outside mounting will require blocking above the window and in the ceiling to mount a roller shade outside of the window frame.

Outside Mount-Shades-05.png


With the growing popularity of metal framing or metal studs being used for both walls and ceilings it is very important to note that this is NOT considered adequate blocking for drapery due to the lack of substance for the screws to grip (see image below).

Wood vs. metal.png

It should also be noted that if renovation entails placing drapery in areas where old/existing drapery had not been previously, a drapery project manager may ask that blocking be added or it's existence confirmed prior to install. 

We hope this has provided a better understanding of the blocking concept. While we all wish it was just about the Lego pieces, alas it is not. Although after this hopefully it seems just as simple and easy.

Download the quick and easy Resource Card on blocking, for a go-to tip sheet in times of need.