Dear Mr. Raja P M,
Extract of Section 44AD with regard to eligible business is as follows,
"eligible business" means,—
(i) any business except the business of plying, hiring or leasing goods carriages referred to in section 44AE; and
(ii) whose total turnover or gross receipts in the previous year does not exceed an amount of 58[two crore rupees].
There is no exclusion of carpentary business and more over it is an exclusive definition, wehere in business of plying, hiring or leasing of goods is excluded.
Also, Sub Section 6 of Section 44AD excludes the following,
The provisions of this section, notwithstanding anything contained in the foregoing provisions, shall not apply to—
(i) a person carrying on profession as referred to in sub-section (1) of section 44AA;
(ii) a person earning income in the nature of commission or brokerage; or
(iii) a person carrying on any agency business.
Here as well, carpentary business is not excluded.