How to Install Spectis Urethane Crown Moulding and Cornice

Spectis’ polyurethane cornice installation method can be easily applied by most skilled craftsmen. A quick, clean and very secure installation is achieved using PL Premium adhesive and low root style wood deck screws. 

Spectis polyurethane cornice can be installed over almost any clean interior or exterior surface. It should not be installed over wallpaper as the paper may separate or the adhesive may stain the wallpaper. 

Moulding which has been stored in “hot” areas must be allowed to “acclimatize” to the location of installation for at least 48 hours prior to installation. (Just as wood requires) Do not install product that has been sitting in a hot trailer or the sun without allowing for this acclimation. Doing so may result in excessive shrinkage which may manifest itself as joint cracks. Moulding stored in cool areas can be installed without product acclimation. 

To begin, screw a support border on the wall for the moulding to sit on. (An experienced installer can use a chalk line as a reference) Apply copious amounts of adhesive (PL Premium) to all bedding edges of the moulding and all butt joints. Once the moulding is installed, remove the support border and fill the holes. 

Place the moulding on top of the support border and fasten the moulding to the wall and ceiling using #8 low root style wood deck screws, plated for exterior use, and long enough to penetrate well into the substrate. Continue installing lengths of crown using the same method, also applying copious amounts of adhesive on all butt joints and toe screwing the joints together, ensuring the moulding profiles are in alignment. 

On smaller crowns, screw spacing can be as little as 2’, but on crowns over 12” X 12”, screw spacing should be approximately 16” on both the ceiling and wall interfaces. Make sure the screws are sunk in the surface of the moulding, as it is necessary to fill in the screw holes with exterior grade, non-shrinking, sandable, and paintable filling products such as automotive grade “bondo”. See “Finishing”.

RECOMMENDATIONS 

1. Before any adhesive is applied, cut and fit each piece of moulding. Use standard woodworking tools when working with Spectis High Density Polyurethane product. Although most of our smaller mouldings can be miter cut on a compound miter saw, it is recommended (on larger crowns it will be necessary) to construct a miter box and use a hand saw to make the cuts. (See page 237) This will ensure that the cuts are made with the correct angles and remove any guesswork trying to figure out table and blade angles on a miter saw.

2. It is possible to install moulding by two separate methods. The first is to begin installing moulding in the most inconspicuous corner, and work around the room in sequence until all the moulding is installed. (Keep in mind that the it may not be possible to have the pattern match at the last joint or corner) The second method is to install short, prefabricated corner elements and run straight moulding between them, which can reduce the difficulty in making good miter joints on long moulding sections. However, the latter procedure does not work well with mouldings which have repeating profiles. 

3. It may be necessary to install extra blocking behind the moulding for additional support, especially on large crowns, where it is not possible to screw directly to the wall. 

4. Although every attempt is made at the factory to ensure all moulding match end to end, it is necessary to check all moulding for thickness variations. It may be necessary to remove material on some edges or add wedges on other sections for good face alignment. Tighten screws in a sequence, which allows for good alignment.

5. It may be necessary to “toe screw” moulding joints together for good alignment. 

6. When installing the last piece of moulding on a run, cut the section long by 1/4” and “snap” it into place, to ensure a snug fit. 

7. Excess adhesive should be removed immediately. Once cured, it will be necessary to use a knife to remove the adhesive. Wedges can be trimmed or removed once the adhesive has stiffened. 

8. Screw holes, wedge gaps and joints can be filled only after the adhesive is cured, approximately 24-48 hours. Use exterior grade, non-shrinking, sandable, and paintable filling products for both interior and exterior applications, as they tend to be of higher quality. Be sure to apply the filler in a fashion, which make for easy sanding. i.e. do not apply more than is necessary. More than one coat may be needed to get satisfactory results. 

9. The product comes from the factory with two coats of paint. The final coat is a UV stable primer, which is ready to receive a site applied finish. (See “Finishing”) Spot prime areas where necessary and paint the prepared product using high quality products, which are compatible with each other. Be sure to select the proper grade for the installation, exterior or interior. High gloss and dark colored products are not recommended since any imperfection in the installation or product will be easily visible. 

10. It is necessary to use copious amounts of PL Premium adhesive on all bedding edges and joints for warranty to be valid.