Controlling Wall Materials through Base & Top line extensions

If you have gone through the process of developing a wall type in Revit, then you may have noticed that there was little to no control for these materials when it comes to defining offset distances from the top or bottom of the level the walls are placed on.

This can only be done if you create a base/top line extension parameter.  To create this parameter first you must go to the type parameters of a wall type you want to modify.

Then go to the wall assembly by selecting the "structure" parameter button.

Once there make sure that your preview window is turned on and that you have the view set to section view which will activate the lower portion of the edit assembly window.  Otherwise you will not be able to continue with the next steps.  I also prefer to zoom in on the upper or lower portion of the wall depending on which part of the material you are trying to modify.

Select the modify button, then when you bring your mouse into the preview window you will see that the lower or upper portion of each material will be highlighted as you place your cursor over the bottom or top of each material.  Click on one material and then you will see an icon which looks like a lock become visible.  If you click on the lock it will be change its display from looking locked to unlocked.

This will now create a new parameter within the properties of the wall that will be visible after you leave the type properties dialogue box and go to the instance parameters of the wall.

Now in section if you select the wall some new arrow grips will be visible that will allow you to manually adjust the height of the newly unlocked material allowing more control for material placement making your wall assemblies more realistic to true construction design.

I created the brick ledge on the lower wall using a wall reveal with the default profile size that is given.  You can apply a specific reveal within the properties of the wall if you want, but thats another blog all together.