For a national campaign, you should use a combination of online marketing and direct mail along with sales calls. Design a terrific website and invest in a pay-per-click campaign on the major search engines. 

Create a top-quality direct-mail package, complete with four-color photography of your product and a persuasive cover letter. You'll need to contact a list broker for the right direct-mail list to reach individuals with the correct title at major homebuilding companies. Or consider contacting one of the larger trade magazines to rent its subscriber list. 

If you can't afford to mail to the whole list, you can probably rent it by state or major metropolitan area. Follow up your mailing with phone calls for an effective one-two punch. Recipients of your direct-mail piece should be able to find you easily on the web and learn more there, as well.